McCallum Drone Valves These elastic drone valves can be inserted into the bottom of your drone stocks to help improve strike-ins and cut-offs. Wrap the threaded portion of the valve evenly with waxed hemp, until it fits snugly into the base of the stock. Install the valves from inside the bag, fitting them into the bottom of the stocks. You can fine-tune the valve tension by pulling the elastic gently, then sliding the small rubber stop to the desired position. Note: A zippered pipe bag is required for installation.
