The YD wiper is the premier design among high performance, snap-in
excluders. Featuring a secondary O.D. lip which seals against the
shoulder region of the gland, the YD prevents water and other
contaminants from entering around the static side of the wiper. For
ultimate performance, the YD also incorporates an aggressive,
knife-trimmed wiping lip to ensure maximum exclusion along the rod.
A true zero-radius lip provides the most effective wiping action available.