The coil jig is designed for use with RTA or RDA tanks, providing a tool for precise coil wrapping. It includes post sizes of 1.5mm, 2.0mm, 2.5mm, 3.0mm, and 3.5mm, each 13mm in length, allowing for customisation of coil wraps. The jig is made from polished stainless steel and measures 10.49 x 5.79 x 1.19 cm, weighing 18 g.