Better than electrical tape by far!
Used this on vehicles (starters) and trailer lights. Easy to use, looks like a professional fitting, and seems to hold tight.
Verified Buyer · Verified Purchase★ Verified
3:1 Dual Wall · 10ft Short Pack
1"
3:1 Heat Shrink
Fits300–400 MCM25.4mm
1 inch heat shrink tubing fits 300–400 MCM conductors and large multi-wire bundles, and it covers the lug barrels used on 4/0 AWG cable. At 25.4mm expanded, it slides over the conductor or bundle and recovers to about 8.5mm, so a single size grips a wide span of diameters — the practical advantage of a 3:1 ratio over 2:1 at this scale. Typical work: sealing cable entries at panel knockouts, finishing conduit terminations, and jacketing switchgear and motor control centre terminations. Because a bundle is never perfectly round, the hot-melt inner wall matters more here than on a single conductor. It flows at 120°C and fills the valleys between conductors that a single-wall tube would simply bridge, leaving a leak path straight through the middle. UL 224, 600V, -55°C to +125°C. The 10ft pack is the sane quantity for a size used at a few penetrations per job.
★★★★★4.7 · 225 verified ratings across the Helixal range
19 in stock · Ships in 24h
Order up to 19 online · need more? Trade pricing
Size1" · 25.4mm
Click any size to navigate · 10 ft per roll
$13.9910 ft spool
→ Dispatched within 24 hours — delivered in 1–3 days→ 30-day money-back guarantee — 30 days to return it
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SKU: B0FJNCQVY1 · 1" (25.4mm) · 10 ft
Spec Sheet
1"
data sheet.
Full industrial dual-wall adhesive spec in a convenient 10ft pack. Same 600V rated, waterproof polyolefin construction as the large bulk rolls.
Imperial Size
1"
Expanded diameter
Metric Size
25.4mm
Nominal
Roll Length
10 ft
Per spool
Wire Gauge
300–400 MCM
Bare conductor
Shrink Ratio
3:1
Dual wall
Construction
Dual Wall
Adhesive inner liner
Inner Layer
Hot Melt Adhesive
Waterproof seal
Voltage Rating
600V AC
UL 224 — 600 V rms
Temp Rating
-55°C to +125°C
Continuous service
Shrink Temp
100°C (212°F)
Shrinking starts
Adhesive Flow
120°C (248°F)
Keep heating until it shows
Material
Polyolefin
Outer sleeve
Flammability
Self-extinguishing
UL 224 Recognized
Color
Black
Standard finish
Standards
UL 224 Recognized
UL file E361230 · RoHS
UV Resistance
Yes
Outdoor safe
Waterproof
Yes — adhesive seal
360° coverage
Sizing over a connector? The Wire Gauge row above is for bare conductor. Heat shrink must be sized to the widest point it passes over, so a crimped butt splice or lug barrel needs a larger tube than the wire alone — a 22–18 AWG splice barrel measures 5–6mm, a 16–14 AWG barrel 7–8mm, and a 12–10 AWG barrel 9–11mm. Measure the barrel, allow about 20% clearance, and confirm the recovered diameter is smaller than the narrowest thing the tube must grip. Use the size calculator.
What the
trade says.
Verified Buyers ★ · Full Range4.7★★★★★225 ratings · 84% 5-starCombined verified-buyer rating for every Helixal product — all ratios, all sizes — not this size alone.
Good quality and sealing heat shrink
Heat shrink works good. Makes a nice sealed wire connection. Better than pre-cut heat shrink — you can make whatever length you want.
R Davis · Verified Purchase★ Verified
Smart format for repair work
Great for keeping several sizes on hand without the bulk. Same quality as the large rolls — the adhesive seals perfectly every time.
Travis M. · Verified Purchase★ Verified
Customer Reviews
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Sizing & Application — 1 inch, 10ft pack
Tubing you use twice a year should not be bought thirty feet at a time.
1 inch (25.4mm) covers 300–400 MCM conductors, large multi-wire bundles and the lug barrels on 4/0 AWG. It recovers to about 8.5mm, so one diameter spans what two or three 2:1 sizes would need. It is also a size that a maintenance department genuinely uses two or three times a year, which makes how long the rest of the roll sits a real consideration rather than a hypothetical one.
Adhesive-lined tubing is a consumable with a shelf life
The polyolefin outer wall is stable for years, and nothing about storage will stop it recovering. The hot-melt liner is the part that is worth thinking about. It is a thermoplastic adhesive, and like any adhesive it performs best fresh and stored in reasonable conditions — cool, dry, out of sunlight, not next to a heater or in the cab of a truck through a summer.
Buy thirty feet of a diameter you use twice a year and the back half of that roll is being applied five or six years after it was made, quite possibly having spent those years in a van. The tubing will still shrink. Whether the liner flows and bonds the way it did when it was new is a question you would rather not be asking at a bulkhead penetration.
Ten feet at this diameter is four to six terminations — a job, or a year of them. It gets used while it is fresh, and the next pack is a current one. That is the substantive argument for the short format at large diameters, and it is a different argument from the one about price.
1 inch short pack at a glance
| Property | Figure | Why it matters |
|---|---|---|
| Expanded diameter | 25.4mm (1") | Passes over 300–400 MCM and 4/0 lug barrels |
| Recovered diameter | ≈8.5mm | One size spans what two or three 2:1 sizes would cover |
| Typical bundle OD | Up to ≈20mm | Measure at the fattest point, including tape or lacing |
| Pack yield | ≈4–6 terminations at 8 in | A job, or a year of a maintenance department |
| Storage | Cool, dry, out of sunlight | The hot-melt liner is the age-sensitive component |
| Bulk equivalent | 30 ft roll | Right only if this size is used routinely |
On a bundle, let the tube overlap solid jacket at both ends. Adhesive needs a continuous surface to bond to, or the seal ends where the bundle opens out.
When to buy differently
01 · The bundle is over about 20mm
Clearance goes quickly at this scale. Step to the 1-1/4 inch pack, which clears roughly 25mm.
02 · You terminate this size monthly
Then the roll gets used while it is fresh and the shelf-life argument falls away. The 30ft roll is cheaper per foot and the right call.
03 · Dry cable tray and MCC work
For abrasion protection and identification indoors, the 1" 2:1 is the appropriate product; there is nothing there for adhesive to exclude.
04 · Medium-voltage splices
Heavy-wall cable splice tubing is a separate class with its own qualification. Do not substitute UL 224 tubing into a splice kit specification.
Keep reading →1-1/4" 3:1 Dual Wall — 10ft pack for larger bundles · Adhesive Lined Heat Shrink Tubing · 1" 3:1 Dual Wall — 30ft bulk roll
How it shrinks.
01
Measure & Select
Verify the expanded diameter is 20–30% larger than your wire or connector. The tubing must slide freely before heat is applied — if it drags, go one size up.
02
Cut & Thread
Cut to length and thread onto the wire or cable before making the splice or crimp. Overlap each terminal or connector end by at least 10mm for a proper seal.
03
Apply Heat
The tubing starts shrinking at 100°C, but the adhesive liner only flows at 120°C — so keep the heat gun moving past the point where it looks shrunk. Start at the center and work outward to push air toward the ends. Adhesive will appear at the tube ends — that is your visual seal indicator.
04
Inspect
The tubing should be tight and uniform with adhesive visible at both ends. No gaps, lifting, or cold spots. Pull-test the finished connection to confirm the adhesive bond.
Size ReferenceExpanded vs.
Expanded vs.
recovered.
Actual 1" tube at full expanded diameter (25.4mm) and after heat recovery. Use this as your fit reference before cutting.
Expanded: 25.4mm — slides over 300–400 MCM
Shrink ratio: 3:1 on full heat
Use it on.
01
Try Before You Buy Bulk
Order a 10ft pack to verify the size fits your connector before committing to a large roll. Test fit, shrink one piece, then buy the bulk roll with confidence.
02
Field Repair Kits
Keep a set of short rolls on the service van or boat. Enough for any repair job without hauling large rolls — one 10ft roll handles most splices.
03
Stock Multiple Sizes Cheap
For the same cost as one large roll, stock several different sizes in short packs. Covers more connector diameters for the same investment.
04
Marine & Outdoor Spot Repairs
Seals individual connections on boat wiring, outdoor electrical, and trailer harnesses. Same waterproof adhesive seal as the large rolls — just 10ft.
05
Low-Volume Production
Ideal for small-batch cable assembly and prototype builds where a full bulk roll would sit unused. Cost-effective for runs of fewer than 50 connections.
06
One-Off Automotive Builds
Custom automotive and motorcycle builds often need several sizes in small quantities. Short rolls let you match every connection without leftover material.
Size Guide
1" Questions.
Technical Guides
All Guides →From the Blog
Free Tool
Heat Shrink Size Calculator
Read Guide →Ratios2:1 vs 3:1 vs 4:1 Heat Shrink Ratio Guide
Read Guide →Complete GuideHeat Shrink Tubing: The Complete Guide
Read Guide →SizingSize Chart & Selection Guide
Read Guide →How-ToHeat Shrink for Battery Terminals
Read Guide →AutomotiveAutomotive Wire Protection Guide
Read Guide →Also available — 1" in other lines
All 13 sizes.
View line overview →3/32"2.4mm10 ft1/8"3.2mm10 ft3/16"4.8mm10 ft1/4"6.4mm10 ft5/16"8mm10 ft3/8"9.5mm10 ft1/2"12.7mm10 ft5/8"16mm10 ft3/4"19.1mm10 ft
Current1"25.4mm10 ft
1-1/4"31mm10 ft1-1/2"38mm10 ft2"50.8mm10 ftRecovered diameter is approx. 1/3 of the expanded size shown · All sizes ship to USA & Canada