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
1-1/4"
3:1 Heat Shrink
FitsLarge bundles31mm
1-1/4 inch heat shrink tubing handles large multi-wire bundles and industrial cable assemblies where a single large-diameter sleeve provides both mechanical protection and a professional finished appearance. At 31mm expanded diameter, this tube accommodates cable bundles up to approximately 25mm across, shrinking to around 10mm recovered diameter. The 3:1 ratio and adhesive inner liner make it suitable for sealing conduit entries, large lug terminations, and bulkhead penetrations where moisture ingress must be prevented. For high-value jobs where you need to verify the fit before committing to a large bulk roll, the 10ft short pack lets you test the application and confirms the right size before purchasing the 20ft large roll.
★★★★★4.7 · 225 verified ratings across the Helixal range
28 in stock · Ships in 24h
Order up to 28 online · need more? Trade pricing
Size1-1/4" · 31mm
Click any size to navigate · 10 ft per roll
$17.8910 ft spool
→ Dispatched within 24 hours — delivered in 1–3 days→ 30-day money-back guarantee — 30 days to return it
Qty
1
Secured by Stripe · No account needed
→Ships USA & Canada
→ISO 9001
→Ships 24h
SKU: B0FJNRYMSL · 1-1/4" (31mm) · 10 ft
Spec Sheet
1-1/4"
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
1-1/4"
Expanded diameter
Metric Size
31mm
Nominal
Roll Length
10 ft
Per spool
Wire Gauge
Large bundles
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 — 1-1/4 inch, 10ft pack
Glands vary. Measure the one in front of you before you buy twenty feet.
1-1/4 inch (31mm) takes large multi-wire bundles and industrial cable assemblies up to roughly 25mm across, recovering to about 10.3mm. Most of its work is at penetrations — bulkheads, gland plates, conduit entries. Those are the applications where the catalogue dimension and the thing on the boat are least likely to agree, which is exactly what a ten-foot pack is for.
The three measurements to take before committing
First, the widest point the tube must pass over cold. On a penetration that is usually the gland body or the compression nut, not the cable, and glands from different makers in the same nominal thread size vary by several millimetres across the flats. Measure the fitting you are actually using.
Second, the narrowest point the tube must close onto. The recovered diameter here is about 10.3mm, so anything thinner is being sleeved rather than gripped, and a sleeve at a penetration is decorative. Take this measurement on the cable at the point the tube will end, not somewhere convenient.
Third, the length of clean jacket available on the wet side. Adhesive needs bond area — aim for at least 25mm of continuous, uncontaminated jacket, wiped with isopropyl alcohol and left to flash off. If the fitting sits close to a break-out, that length may simply not exist, and it is far better to discover that with a ten-foot pack in hand than with a twenty-foot roll on the invoice.
1-1/4 inch short pack at a glance
| Property | Figure | Why it matters |
|---|---|---|
| Expanded diameter | 31mm (1-1/4") | Clears bundles and glands up to about 25mm |
| Recovered diameter | ≈10.3mm | Below this the tube sleeves rather than grips |
| Overlap to allow | ≥25mm of clean jacket | Adhesive needs bond area, not just contact |
| Surface prep | Isopropyl alcohol, flashed off | Hot-melt bonds poorly through oil or release agent |
| Pack yield | ≈4–6 terminations, or 2–3 penetrations | One job, with material to redo a piece |
| Bulk equivalent | 20 ft roll | Twice the pack — order once the fit is confirmed |
Large diameters need longer, gentler heating. The outer wall reaches recovery temperature well before the liner flows through the full thickness.
When the measurements point elsewhere
01 · The assembly is over about 25mm
Step to the 1-1/2 inch pack, which clears roughly 30mm. A tube that has to be worked on by hand will not seat evenly.
02 · The cable is under about 11mm
The recovered wall will not close onto it. Drop to the 1 inch pack, whose floor is about 8.5mm.
03 · Indoor bundling and identification
The 1-1/4" 2:1 does mechanical protection and labelling in dry cable trays and MCC panels at a lower cost per foot.
04 · Rated fire or pressure barriers
A rated bulkhead penetration needs a listed transit or firestop system. Heat shrink seals against water; it is not a rated barrier assembly.
Keep reading →1-1/4" 3:1 Dual Wall — 20ft bulk roll · Adhesive Lined Heat Shrink Tubing · What Size Heat Shrink Tubing
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.
Watch
All Videos →See 1-1/4" In Use
Size ReferenceExpanded vs.
Expanded vs.
recovered.
Actual 1-1/4" tube at full expanded diameter (31mm) and after heat recovery. Use this as your fit reference before cutting.
Expanded: 31mm — slides over Large bundles
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
1-1/4" 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 — 1-1/4" 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 ft1"25.4mm10 ft
Current1-1/4"31mm10 ft
1-1/2"38mm10 ft2"50.8mm10 ftRecovered diameter is approx. 1/3 of the expanded size shown · All sizes ship to USA & Canada