The kind guys over at Vastfire sent me one of their taclights. The taclight has all the parts needed to attach it to a gun. I have installed it on my G&G CM16 airsoft rifle.
All round this is a great flashlight and I would fully recommend it to anyone in the market for one.
Link to buy the flashlight here: https://www.amazon.co.uk/gp/product/B01MQRI8CG/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1