Version 4 is our latest version, incorporates version 3 onto a rolling cradle.
Version 3 incorporated version 1 with a bearing ring, large deck with a glide ring installed and wood rails with walk over ramp.
Version 2 attempt to use pressure treated wood. Only lasted about 2 weeks and started to fail.
Version 1 was a simple pipe structure that pivoted on a single center bolt, but dragged on top of the rails.