M23 Standard Threaded & Checkmate™ Connectors Amphenol Sine Systems M23 Standard Threaded and Checkmate™ Connectors are high-performance, cost-effective connectors designed with Checkmate quick-locking technology. These connectors feature superior environmental seal retention and are compatible with existing industry-wide standard products. The M23 standard connectors are available in 6, 8, 9, 12, 16, 17, and 19 positions. The M23 Checkmate quick-locking connectors feature the Metrifit™ strain relief system that provides 360° EMI/RFI shielding with advanced sealing capability (IP67). The Amphenol M23 Checkmate connectors have distinctive alignment arrows and quick locking reliability.