This is a domeless titanium nail which has a universal joint that has a 10, 14 & 18/19mm male & female fitting. Unscrew the bowl and srew it on to the other side of the body to switch from male to female. It goes onto a dab oil wax rig bong which has a 10mm, 14mm or 18/19mm male or female joint fitting. It has ridges directly under the bowl which are designed to keep the nail cool and keep the heat from spreading down to the joint.
To use place it on your bong fitting joint, use a torch to heat up the outside top rim of the bowl until it gets hot, if it gets red hot wait for it to cool down a few seconds than dab it so the concentrates do not burn.
Domeless nails are ideal compared to the traditional nail & dome method, Domeless nails are built with a bowl that is meant not to spill any concentrates so you don't loose any, also the air flow chamber is directly next to the dabbing area allowing the smoke to flow in the bong fast without wasting any smoke.