This Sea & Sea o-ring set is for the YS-110, YS-27, YS-30TTL, 30II, 90TTL, 90 Auto and 90DX strobes. The o-ring resembling a thick rubber band is designed to establish a watertight seal when going underwater.
Manufactured to precision tolerances required to hold a pressure seal on your housing and made of elastomeric material, it provides the means by which a watertight seal is formed.
O-Ring care guide