what size male do I need to attach to my accesory?
It looks like it's a 1" female fastex buckle, so it would be designed mount to a 1" male fastex.
*HOWEVER* IMO that makes the thing way to "dangly" to dive with. I use this for my computer console. I removed the 1" fastex female piece and replaced it with a 1" plastic D ring. (Careful opening the body; the retractor spring could unwind. If you're not comfortable with that, just ignore the female fastex buckle, or break it off).
Then I mount the retractor *body* to my BC chest strap with a piece of 1.5" dia heatshrink tubing 2.5" long, so the retractor ring is high and tight on my sternum. Tie the D-ring, or the buckle, or the buckle attach on the retractor, to the BC shoulder strap for added security.
Then a SS boltsnap tied to the computer clips on the retractor ring while I'm diving.
This should be a 1 inch clip