Air Gap Manifold Opinions

Has anyone used or heard of these Air Gap manifolds? They're at least $100 less expensive than Edelbrock version. I wonder if this is a case of "you get what you pay for". Anyone using them or have any info? Thanks Mike
http://cgi.ebay.com/ebaymotors/ws/e...MEWA:IT&viewitem=&item=180089452049&rd=1&rd=1