SILCA 741 Leather Piston Gasket (formerly 74.1)
Since the 1960's all SILCA leather gaskets have come from the same leather converting house in the fashion district of Milan, Italy. For more than 5 decades the same supplier has cut these washers from the excess material left over from the production of exotic handbags, Italian luxury cars interiors, and high-fashion luggage. A small press is used to trim and pressure-form these leather washers into durable pressure gaskets.
From a purely functional standpoint, inexpensive o-rings are most commonly used in this application, but no o-ring can match the smooth feel and zero-stiction action of a leather gasket. It is common today to find SILCA leather gasket pumps throughout the professional peloton (especially during the spring classics) as o-ring seal pumps struggle with heat and often are unable to seal once the pump barrel is hot from inflating more than a few wheels.