5507-1503 (BCR) Burton Compatible 55 series BULKHEAD PIN INSERT 20 shell 3 pin BCR Bulkhead Connector Receptacle (5507) Less expensive than the FCR, this is the standard receptacle mount. It may be used with any plugs. When using the BCR with a right angle plug (CCP-RA), a BCR retaining ring must be used instead of tapped threads. This is due to keyway orientation