At times I'm lacking these as rebuildable cores are getting harder to find.
A core charge applies and will be charged afterward if you don't have any cores to send back.
Send the core back in the box the refurbished core came in!
IMPORTANT INFORMATION FOR RETURN OF CORE:
Do not disassemble brake calipers!
Wire and other connections must be intact, and undamaged.
If either of these is drilled out, the core won’t be approved.
Installation pin holes must be undamaged.
Pad resistance mustn’t be worn.
Casting must be intact adjacent to o-rings and dust boots.