Original classic-looking Monza non-locking brushed aluminum flip cap, with the mounting collar to fit tank included. The actual cap screws onto a special brass adapter that is a very tight press fit onto the neck of the tank, which can be glued on for extra safety.
To fit the collar for this cap, you will require 10mm (just over 3/8") of tank neck accessible above the body seal to allow fitment. Now with chrome-on-metal catch for longevity.