SPD-1 LEGACY series represent Summit Research early work. These heads hold records in labs for both potency and output speeds; having been the most duplicated distillation heads on the market for a reason. These fabulous heads operate with greater throughput then import knockoffs or competitor heads. Forget the leaks with two piece heads and stick with the LEGACY series for a entry level price with outstanding performance. Made in USA. comes with a #24 main and discharge joint. GL14s included.