Universal Conn, 20J & 21J Tuba 3 valve, 24J & 25J 4 valve. Allied A383, D19mm x L63mm. See my item ID# 16184 or 16967 for genuine King tuba & sousaphone springs. See item ID# 16128 for Conn 20K & 22K Sousaphones. See my item 28067 & 28068 for a smaller Besson type spring.
