You need a Bristol wrench. Those normally come in sets that will have one of the proper size. Glen, K9STH Website: http://k9sth.com --- On Mon, 12/8/08, Francesco Ledda <frledda at verizon.net> wrote: From: Francesco Ledda <frledda at verizon.net> I need to get the vfo shaft collar loose. It looks like I need a flute wrench; which size do i need?