These stainless steel nails by Black Leaf are for oil use and can be inserted into your connector and the head is adjustable by screw. For usage, the pin head needs to be heated by a lighter until it glows hot red. It is the stainless steel material that allows this to heat your oil or concentrate to the optimum temperature. The stainless steel is heat resistant. These adjustable nails are cut for 18.8mm & 14.5mm Joint.