Part # Shrink Ratio  Material  Min Supplied ID  Max Recovered ID  Nom Recovered Wall  Temperature  Ratings 
FIT-321-1/4 3:1  Dual Wall Flexible PO Thk Wall  0.24  0.08  0.04  -55 to 125  AMS DTL-23053/4 Class 3, CA Prop 65, CSA 198, RoHS, UL 224 
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1) Tubing Type Dual Wall Heat Shrinkable Tubing
2) Tubing Material Dual Wall Flexible PO w/Thick Wall Adhesive
3) Minimum Supplied ID(In) 0.240
4) Maximum Recovered ID (In) 0.080
5) Nominal Recovered Wall Thickness(In) 0.040
6) Nominal Recovered Melt Wall (In) 0.020
7) Color(s) BLACK
1) UL Standard 224 125°C / 600 VRMS
 All Tubing Flame Test 
2) CSA International Standard 198 
3) Other AMS-DTL-23053/4, Class 3 
1) EU Directive 2011/65/EU(RoHS2):
 All materials used in the manufacture of this part are in compliance with European Directive 2011/65/EU regarding the restriction of use of certain hazardous substances in electrical and electronic equipment.
2) California Proposition 65:The outer surface materials used in the manufacture of this part meet the requirements of California Proposition 65.
Physical & Mechanical Properties
1) Temperature Range -55 to 125°C 
2) Shrink Ratio Approximately 3:1 
3) Full Recovery Temperature 110°C 
4) Minimum Shrink Temperature 110°C 
5) Tensile Strength 1500psi, Min ASTM D638
6) Elongation 250%, Min ASTM D638
7) Cold Impact(-55°C) no cracking ASTM D746
8) Heat Shock(250°C,4hrs) no cracking AMS-DTL-23053
9) Secant Modulus 2.5x10 4 psi, Min ASTM D882
10) Longitudinal Change +1%/-15% AMS-DTL-23053
11) Shelf Life 3 Years @ 18 to 35°C 
Electrical Properties
1) Dielectric Strength 300 V/mil, Min ASTM D876
2) Volume Resistivity 1x10 12 ohm-cm, Min ASTM D876
Chemical Properties
1) Water Absorption 1.00%, Max ASTM D570
2) Corrosion(0°C,16hrs) no corrosion AMS-DTL-23053
3) Fluid Resistance(23°C,24 Hrs) 900 PSI, Min AMS-DTL-23053
4) Fungus Resistance Pass AMS-DTL-23053
5) Halogen Free No 
6) Lead Free Yes 
Packaging
25X4 FT, 20X6 IN

Our FIT heat-shrink tubing offers a reliable way to protect and seal terminations or add additional mechanical ruggedness. FIT preferred heatshrink products are made from premium compounds under the tightest manufacturing controls. This means FIT will consistently have excellent physical characteristics such as low longitudinal shrinkage and wide temperature ranges while providing an elegant appearance when used alone or on OEM equipment.

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