ARF - Almost Ready to Fly. A MUST have accessory to fly those rockets HIGHER and HIGHER! And flying higher is what model rocketry is all about! And having fun, of course. Designed specifically for use with the 2884 Red Rider, 2485 L.G.M. 0095, 2492 Spirit and 2495 Chiller model rockets. Adds up to 800 feet. Booster uses one D12-0 model rocket booster engine (sold seperately).