the front thread of your iris is removed with the factory spanner
• 501`s adaptor thread is screwed into the front of your iris
• the iris and 501 are attached to your rearsight after loosening the rail carrier`s allen screw
• the lens is inserted in the lens holder which can be removed from the carrier rail if required
• the lens holder is positioned to the rear of your iris as required and locked on the carrier rail
• our system allows alignment of the carrier to suit you