A variable-focusing head cap assembly is used in a flashlight having a barrel and a lamp mounted on one end of the barrel. The variable-focusing head cap assembly includes a tubular coupling sleeve, a parabolic reflector, a cap member, and a generally C-shaped resilient friction ring. The C-shaped resilient...http://www.google.se/patents/US6027226?utm_source=gb-gplus-sharePatent US6027226 - Variable-focusing head cap assembly for a flashlight
