BNC T-connector. With two female connectors and one male.
Used to Split or Combine Video Signals.
Used for 10Base2 Networks.
Wikipedia Info 10Base2 Networks
Works well with RG58 and RG59 Cable.
ReInforced Collar used on Premium Connectors: Do not purchase ones without this collar they snap Easy
APC Part 0769
Belkin Part R6C073