i dont mean to hijack tarmacs thread but to the people who want these but dont want to pay 200 then try these, ive used them quite a few times on my zed and have been a big help, even had my zed on them for a week and they never budged. Great price too, not sure if a lowered zed would be able to use them on their own though.
http://www.towsure.com/product/Chockmaster