A slip joint pocket knife has blades held in place by a backspring. The spring tries to hold the blade closed until it has been pulled past a 90 degree arc from the handle, when the force reverses and springs to the open position. Likewise, if open and the blade is moved back down 90 degrees, the blade would spring shut. Slip joint pocket knives come in a variety of sizes, styles, and blade types. Check out the best slip joint pocket knives you can buy under $50 below.
