Part # Shrink Ratio  Material  Temperature  Ratings 
FIT-321-MS-1 3:1  Dual Wall IRR PO  -55 to 110  AMS DTL-23053/4 Class 3, CA Prop 65, CSA 198, RoHS, UL 224, UL VW-1 
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1) Tubing Type Dual Wall Heat Shrinkable Tubing (Assortment)
2) Tubing Material Dual Wall Flexible PO w/Thick Wall Adhesive
3) Color(s) BLACK
Supplied ID
Recovered ID
Recovered Wall
Melt Wall (In)
FIT-321-1/8 0.125 0.024 0.037 0.020 5 x 6 IN
FIT-321-1/4 0.250 0.079 0.047 0.020 5 x 6 IN
FIT-321-1/2 0.500 0.157 0.071 0.030 5 x 6 IN
FIT-321-1IN 0.945 0.315 0.098 0.040 5 x 6 IN
1) UL Standard 224 125°C / 600 VRMS
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. Consult Alpha Wire's web site for RoHS C of C.
2) REACH Regulation (EC 1907/2006):
 This product does not contain Substances of Very High Concern (SVHC) listed on the European Union's REACH candidate list in excess of 0.1% mass of the item. For up-to-date information, please see Alpha's REACH SVHC Declaration.
3) 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 

Alpha Wire FIT® Kits are great resources for use in R&D labs, engineering development, and maintenance departments. These kits provide heat-shrink tubing is various sizes and colors in pre-cut pieces up to 6". 

Additionally, our FIT-MGKIT-1 comes with a FIT MINIGUN so you can have everything you need to test our product at your fingertips.  We offer our kits in a variety of colors, sizes, shrink ratios and materials. 

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