The gasket contains a rubber or silicon seal within the case, which keeps water and dust from penetrating the case and damaging the movement. Gaskets are normally placed around the case back, crown, and crystal to seal them watertight. Regular maintenance, including gasket replacement, is necessary for water-resistant watches and can ensure long-lasting water resistance.
Gaskets make a watch rugged for withstanding the outside environment and daily wear while protecting the delicate inner mechanism from moisture and contamination.