The term 'Cleats' covers a multitude of different configurations designed to grip, restrain and secure the load on a rope. This category covers those cleats that are used for quick grip and release in running rigging applications plus traditional shaped cleats for securing a line where adjustment is not the priority.
There are three main designs or concepts for Running Rigging Cleats:
Cam Cleats - This design is based on a pair of ribbed, spring-loaded cams that pinch together and won't let the rope through one way while allowing free movement in the opposite direction. The line can be tightened by pulling through the cleat and released when under load with a firm upward jerk.
Jam C leats - This design is based on a V shaped slot with fluted ribs to provide the grip. There are no moving parts. The jamming element secures the line in one direction and allows release by taking the tension off the cleat and lifting the line clear of the jaws. Clamcleats produce a wide range of jamming cleats for dinghy applications, but also for adjustable fender lanyards.
Roller Cam Cleats - This design works in a similar way to a rope clutch with vertical pressure applied via a single internal cam to grip the rope. The Spinlock version is very compact, efficient and ergonomic.
There is also the traditional shape and design: T or Horn Shape Cleats - These are typically used for e.g. flag halyard cleats, mast base halyard cleats positioned below a winch or clutch.
Cleats for Mooring or Anchoring feature separately.
Please note that Rope Clutches perform a similar function to jam and cam cleats.