A gauge head assembly for use with a magnetically actuated dial includes a cylindrical body formed from a magnetic material having a cylindrical sidewall with an threaded outer surface, wherein the sidewall defines an axially extending passage for receiving a tubular insert formed from a substantially...http://www.google.es/patents/US7690323?utm_source=gb-gplus-sharePatente US7690323 - Gauge head assembly with non-magnetic insert
