CMP Spa Master Massage Jet Internal [1 1 2", Ribbed] [Gray] (23315 241 000) gvt Perma Cast Tool [Brass Relief Perma Cast Tool [Brass Relief Valve Install] from Perma Cast is a practical replacement component for pool and spa service work where the correct fit this part is well suited for a matched replacement approach that restores balance throughout the assembly rather than leaving mixed wear levels in place The CMP Spa Master Massage Jet Internal 23315 241 000 is a 1 1 2" ribbed gray replacement internal for compatible CMP Spa Master jet assemblies This replacement internal is ideal for restoring a spa where existing inserts are worn