Feats
"FYI- the Ironmind grippers are somewhat well known in strength circles. There are five different ones - trainer (100 lbs.), #1 (140 lbs.), #2 (195 lbs.), #3 (280 lbs.), and #4 (365 lbs.). To put these numbers in perspective - I saw an article recently by someone who brought his grippers to this year's Arnold Classic. He got a lot of really big guys to try them - only one person, Manfred Hoeberl, closed the #2. Among those who couldn't get the #2 were Dorian Yates, Greg Kovacs, and powerlifters Ed Coan and Anthony Clark. The #3 (which Hoeberl also closed) has only been "officially" closed by about 10 people, though many super strong guys (World's Strongest Man types, for example) have tried. *Nobody* has closed the #4."
Source       #3 closers

"Manfred Hoeberl recently visited Weider headquarters in Woodland Hills, California and gave Joe and a group of us from muscle & fitness and flex a dramatic demonstration of just how powerful he is.       Taking a full soft-drink can, Manfred wrapped both hands around the metal container. With a loud yell, he squeezed his hands together and blew the top off the can! Soft drink distributors estimate that it takes nearly 600 pounds of force to accomplish the feat. Manfred did it in two seconds. Then, he did it again with another full can just because we enjoyed it so much!" Article at Muscle & Fitness Online, see Links page

"For example, I did a demonstration on a television show in Europe where I turned over 10 cars in three minutes and 20 seconds."
Manfred Hoeberl