1. Threaded connection
A form of connection that is often used by connectors with larger size contacts and working in strong vibration environments. This type of connection can be equipped with a fuse to prevent loosening after the connection is completed. This connection form is reliable to use, but the unloading speed is slow.

2. Bayonet connection
It is a reliable and rapid form of connection and disconnection. Most connectors in the card 121 connection style have a visual indication of proper connection and locking, which can be viewed from the small hole on the side of the connector nut.

3. Plug-in connection method
It is a versatile form of connection. When the plug and socket of the connector are connected and separated, the moving direction is usually a reciprocating linear motion, which does not need to be twisted and rotated, and only needs a small working space to complete the continuous unloading. Common plug connections have two structures of balls or pins. Because there is no mechanical labor-saving mechanism in this connection form, once it is inserted by mistake, the mechanical resistance will increase significantly, and it can be found in time.

4. Cabinet connection
It is a connector for some equipment that needs to be connected blindly near the frame, which can make the electrical equipment lighter and smaller, easier to maintain and more reliable. This connection form makes the operator unable to feel the connection, and a precise positioning device must be designed to avoid forcibly connecting the wrongly inserted connectors together, making the wrong insertion impossible. Cabinet-type circular push-pull self-locking connectors usually use floating or elastic contact design structures to ensure their correct connection.