Silcas unrivaled locking chuck employs a rotating head and a locking side lever to easily lock onto any Presta valve from any angle and hold its seal up to 300 psi. The locking chuck is meticulously constructed in the United States using stainless steel and it’s knurled for good grip in wet or greasy conditions. The chuck uses a high-tech Silca 254 elastomer gasket for excellent sealing and durability.