Heat Shrink Tubing 1/4in x 3in – Black & Red Combo. Package of 1/1 Black, Red 3 in 7.6 cm long sections with a 1/4 in 6.4 mm diameter that shrinks to 5/64 in 2 mm.Features: Cross Linked polyolefin tubing is much stronger than PVC tubing and will not burn like PVC. Heat activated adhesive lining provides impervious seal to salt water, oil, acids, and sunlight as well as providing strain relief. Highest shrink ratio – shrinks to 1/3 original size. Shrinks at 257 deg F / 125 deg C. Operating temperature range of -40 deg C to 110 deg C. UL 224.