Quick Release Barrel Mount
Ring Diameter: 30mm with a 25.4mm insert
Rail Size: 20mm
Tried the barrel mount on a .22 and .308 with a diameter of 14.1mm - 17.5mm. Looks like it should be okay up to 18mm diameter barrel, anything smaller than 14mm should be fine, if not it's simple to wrap something around it.
By flicking the lever out the lower piece detaches. Great for searching with the torch and then snap it back on for the shot.