RNF-100-3/4-2-STK-Heat Shrink Tubing, Flexible Flame Retardant, 2:1, 0.748 “, 19 mm, Red, 4 ft, 1.2 m. The RNF-100 series from TE Connectivity are general purpose, flame retardant, high performance polyolefin heat shrinkable tubing. Features higher level of performance at elevated temperature, mechanical abrasion and fluid resistance.