A drop seat is pair of releasable, elastic bands extending from the rear side of the leg loops and connecting to the rear of the harness. They act like suspenders. These clips allow the leg loops to be lowered when nature calls while mid-route. Women generally appreciate this feature more often then men.
The drop seat feature also makes it easier to entirely remove your leg loops without taking off the harness. Without releasable leg loops, you’d have to be a contortionist to be able to bring your legs up to your chest to slide your legs out. Some wall climbers do this to “bivi in the swami” for added comfort.
Either way, releasable leg loops do not increase the safety of the harness. And, when sliding through course chimneys, the clips on either end of the webbing, which fasten the leg loops to the waist belt, are the quick to wear out. Note: If you see noticeable damage on leg-loop suspenders or drop-seat clips, this is not a sign that your harness is unsafe. These are not load bearing features.