They are secured using a compression tool.
New compression type BNC connectors are high quality connectors that are easy to attach and compatible with RG59 cable. It provides a secure, waterproof connection for RG59 coaxial cable and is easier for camera installation.
CCTV Compression BNC Connector for Coax RG59 Cable for Cameras DVRs
These connectors are more reliable and easier to use than traditional hex crimp BNC connectors
Material: metal
colour: blue&silver
size: Length: about 40mm; diameter: about 14mm
Package Contents:
10pcs X Connector
Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.