PermaSleeve Heat Shrinkable Wire Marker Sleeves for the BMP71 Label Printer. B-342 PermaSleeve Heat-Shrink Polyolefin may be used for both thermal transfer and dot matrix print technology. Material Type: Irradiated polyolefin heat shrink tubing (3:1 shrink ratio) 342 is a UL Recognized Component to UL224 Extruded Insulated Tubing. See UL ...