A Head Catcher is used to "catch" a cable head to prevent the loss of a tool string. The mechanical latch is always in the catch position and must be hydraulically activated to release the cable head. 

The Lee Specialties Head Catcher is a multiple tool/size cable-head catcher. It is durable, easy to use, and simple to maintain. The head catcher is usually installed above the lubricator in a pressure control stack and prevents loss of the tool string.