Yes,inner flat.I have put soap water on the valves;no bubble.I choose ea for the weight they had to handle.The one under the turn table made the most difference and is missed the most.Are the Bright Star air mass/or big foot sand boxes as good?And yes thank you for the Vibrapod info Mate.With no other help I would have tried,but somehow I figured my solution would be more than 6 bucks.