Does 3m coldshrink come shorter than the stated length when expanded, prior to installation. Reason I ask, I got some that are supposed to measure 12" long (8428-12) but I taped the out to only 10.5". Is this normal and will they extend out to 12" once I unstretch them over eva or hypalon. I've never used any of this stuff so I have no experience with it even though I have another piece of stiletto 18" coldshrink that is a few years old, new in package...and that too tapes out to only 16.5". Just wondering if I got burned?