Titan Titanium Nails are designed to fit on the majority of all 14 mm and 18 mm standard tapered male glass on glass ground joints. This nail fits coils with an inside diameter of 16 mm (0.625″) and a maximum coil height of 12.7 mm (0.5″). Two separate pieces assemble to hold the coil safely in place. The E-nail nail uses the same threading and is compatible with the all other E-nail nails. This E-nail insert is 14 mm and 18 mm female and is to be used with standard tapered 14 mm & 18 mm male glass on glass ground joints.