The seal is a neoprene Vacuum rubber seal for a CNC. It works incredibly well. If you try to lift the workpiece the whole bench will lift off the floor. I use my CT24 but I've not used it extensively so I'm not sure about any heat issues. I'll get a splitter for the hose soon so I can still use the CT while using the top which should also help with any over heating and hopefully won't negatively effect the suction strength too badly.
Toby
Toby