The Valterra slide valves have seals either side of the main slide and over time these can wear, causing leaks. These genuine Valterra seals are direct replacements for the original seals.
The seals are simple to replace, just unbolt the 4 bolts around the slide valve and replace, just make sure you install the seals the right way round
Replacement pair of seals for a Valterra 4" slide valve