Since the 1960's all SILCA leather washers 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.
For further information on the 731 Leather Washer, please visit the SILCA resource center.