Key-Write Key Id Sleeves Sleeves Are Colored Heat-Shrink Plastic Yellow Clamshell 8 "KEY-WRITE" KEY ID SLEEVES Sleeves are colored heat- shrink plastic Slide the sleeve over the head of the key and apply heat while holding the sleeve in place The sleeve shrinks to form- fit the key head providing a writable surface The best pen for this use is the "Sharpie" Industrial