a fastener for all - purpose power supplies sockets includes a socket and at least one plug engageable with the socket . the socket has a latch cavity in a lateral wall . the plug has a moveable fastening member that has a first button engaging with a latch bar . the latch bar has a latch head engageable with the latch cavity and a latch tail engageable with a spring strip . the latch head may engage with the latch cavity automatically when the plug is inserted in the socket to form a secure engagement and coupling . upon moving the first button sideward , the latch head will be disengaged with the latch cavity to enable the plug to move away from the socket easily .