SnapLok Large Quick Release Drill Adaptor
 
For use with the 12mm, 15mm, 18mm, 19mm, 20mm & 22mm SnapLok rods and rotary power heads. Made of stainless steel with double buttons for double security and corrosion resistance.
 
This works on the basis of pressure and the angle of the SnapLok rod, so when you are sweeping with the rod at an angle, the downward pressure keeps the rod on the drill adaptor. As soon as you straighten the rod in parallel to the drill adaptor, you can just pull on the drill and the drill adaptor comes out from the rod fitting/ferrule.