The F1051/4 BK005 from Alpha Wire is flexible black heat shrink tubing with a 0.250" (6.35 mm) diameter and a 2:1 shrink ratio, supplied as a 100.0' (30.5 m) length.
The F1051/4 BK008 from Alpha Wire is flexible black heat shrink tubing with a 0.250" (6.35 mm) diameter, a 2 to 1 shrink ratio and a 25.0 ft (7.6 m) length.