The last combat variant of the Ju 87 Stuka and successor of the Junkers Ju 87D was the Ju 87G series. This Stuka variants were built by conversions of the ubiquitous D models. Only the Ju 87G-1 became operational. The Ju 87G was a specialized anti-tank version, fitted with two BK 3.7 (Flak 18) guns hung under the wings just outboard of the landing gears. This 37-mm-gun was a formidable weapon weighting over 363 kg (800 lb) and in wide service as ground-based Flak (anti-aircraft artillery) equipment.