The Skimmer was designed after a number of prototypes and while there are home made options this is perfect for a 600mm lens either on a wimberley head or just on a quick release plate. The size is perfect and the round shape lets you slide it in any direction without getting stuck in sand or mud. When pushing forward it's best to push down on the camera to lift the front edge up. It's expensive as the previous reviewer complains but being in the plastics industry myself I imagine an injection mold of this size costs as much as a small car! The material is indestructible and light at the same time. I doubt this is a high volume item so I'm willing to pay $99 - I saved $20 when I purchased the matching beanbag called the Skimmer sack