Friends, also known as active cams, are metal devices that can be placed in rock fissures, pockets, or cracks to serve as protection points. They come in various shapes, often resembling a hammer with a handle at the bottom and a convex, crescent-shaped cam on top. The size of the cam can be adjusted; it is inserted into the crack in a contracted state and expands to grip once placed. Their working principle is somewhat similar to that of chocks, both relying on fitting securely within a fissure to act as reliable protection. However, Friends are generally easier to remove from the crack and are less likely to be left behind on the wall, making them a preferred choice for traditional climbing routes.
In fact, the general English term for Friends is Spring Loaded Camming Device (SLCD), often abbreviated as "cam." "Friend" is the brand name for Friends produced by Wild Country. For example, BD’s Friends are called Camalots, CCH’s are called Aliens, and Metolius’s are called TCU (Three Cam Unit) or FCU (Four Cam Unit). SLCDs can be broadly categorized by the number of cams into TCU and FCU types, and further divided by stem flexibility into elastic and rigid types, among others.
Friends produced in the United States and the United Kingdom are all of high quality (though different designs have their own strengths and weaknesses), and those from other countries are also usable, at least in terms of affordability. Even the best equipment is useless if you don’t have it when you need it.
Note: Chocks are metal pieces of varying sizes and shapes that can be placed in rock fissures, pockets, or bridges to secure a protection point.
Using chocks as protection points requires extensive gear experience. The user must be very cautious to ensure the chock does not move or dislodge under possible force directions. Non-mechanical chocks mainly rely on their asymmetrical shape and the variations within the fissure to hold in narrow sections. Friends, on the other hand, can adjust their size and shape—they are inserted in a contracted state and expand to grip, making them convenient to use and widely applicable, thus an excellent choice for traditional climbing routes. Familiarity with the diameters and suitable applications of various chocks can greatly improve operation speed, and it may be helpful to mark the stems of the chocks when necessary.