Originally Posted by Pyolet
Slides were first offered in 2000 models. The inflated seal system is effective and quite expensive to replace.
Correct, and to expand, all Foretravels (save maybe the weird Sprinter-based micro villa) use the HWH air bladders.
You're looking at several thousand per bladder for replacement (usually around $1-2K for the bladder, 8-16 hours labor), and since they are rubber they do age out. Data seems to indicate a 7-10 year lifespan. The 2000-2001 coaches (and maybe some 2002) require the entire slide to be removed (by forklift) in order to replace the bladder.
The slide bladders do give a clean look to the outside of the coach, but servicing them is not a DIY job at all.