Most rock-climbing equipment is not suitable for tree climbing. The harnesses found in rock climbing are designed for the event of a fall with a quick recovery back to the rock surface with hands and feet. They are not designed for prolonged suspensions in midair. Throw a rope over a branch, clip yourself in to your skimpy rock-climbing harness, and hang for ten minutes. Tell us when you start singing in a higher octave.
Saddles come in two styles.
Two straps wrap around the thigh near the crotch. Butt strap saddles use a strap that goes across the climber's bottom. They feel like one of those swing-set seats that have a flexible seat. You must be careful to use a butt-strap saddle that has two smaller straps that pass through your crotch and connect to the front of the saddle. They prevent you from slipping out of the saddle while hanging upside down or getting in contorted positions.