Seat (Lectric plush) sits on rails like normal seats. But this is a weird note to make. The co-worker I gave the plush seat to has a Addmotor with a regular, non-suspension post. When we pulled the Addmotor flat/thin seat off and went to mount the Lectric plush seat the rails required us to squeeze the Lectric rails to make it fit the Addmotor post. I've seen this strange rail issue in the past. A set of slip joint pliers and some hand strength can make the rails fit. Not sure if a rail would break down the road from being rigged but that's what we had to do. The Addmotor guy just plays around in the neighborhood, no commuting or far rides for him.
Cloud 9 makes some very plush and comfy seats, and their quality is always top notch. I've always liked Sella Royals myself and the ones Wal Mart sells are made in Italy, and my wife is Italian! I feel like I support some distant relative when I buy one.