a much cheaper option for your cool airsoft gun, a cool and simple flash light - the OP 515 Modular Vertical Foregrip Laser Sight
fit it under a standard 20mm rail then you are good to go. the buttons are a little bit hard, but still easy to press as they are in good positions on both left and right sides, so, ambidextrous.
takes two cr123a batteries, remove the lid at the button then plug them inside the grip. package comes with an allen key, no batteries included
a simple and easy alternatives for those who need some light