Zhe Jiang Senior Guide Co., Ltd produce and supply support union of ball screw (ball screw coupling) including size: SRJ-20C,SRJ-30C,SRJ-40C,SRJ-55C,SRJ-65C. But for one specification, custom should confirm (H8)d1xd2 holes size. One specification, there are different d1 and d2 size holes for cutomer's options.