Battenfeld (Caldwell) have done an incremental upgrade of the Lead Sled and named it the Lead Shed Plus.
The main improvement is the elevation ram which has been redesigned to prevent movement. No word on pricing or availability.
The Lead Sled is designed to be used when shooting magnum rifles. The sled is packed with weights, such as lead shot, which decreases the effect of recoil. Below is a screen capture from a Caldwell promotional video of a guy shooting a rifle with an egg between his shoulder and the lead sled.