The rear panel of Storm II is made from 6mm Grade 5 Titanium, with two spikes holding people off that. The weak points at the back are the aerial and link door.

The link door adds another 6mm of Titanium over the rear armour panel and slides open and closed - its designed to take direct impacts if were cruising about in reverse. The aerial is firly attached enough that you can pick the robot up with it.

Storm II may not have a wedge on the back, its its still solid enough to do the business

Ed
http://www.stormrobot.comhttp://www.stormrobot.com