HellermannTyton Heat Shrinkable Tubing 3:1 - Flame retardant, TA37 Range - HellermannTyton 315-13004, The HellermannTyton 315-13004 is a Heat Shrink Tube from the TA37 range. This 3:1 Ratio heat shrink has a low smoke index and excellent flame retardant properties to meet strict fire security standards in electrical insulation. HellermannTyton 315-13004 3:1 Piece Heat Shrink Tubing Black 4mm (1.2 metre)