To answer your basic question oneslave4me in a word NO. Allalone is spot on on this, if DH is 300# then you need a hard point that will hold at least 1200# or more. Even if you try to use them for a minute ot two you will porbably find that they won't hold and DH's head hitting the hard concrete floor for 6' 7" is enough to kill him. Why take the risk?

DH's plan for "indutrial strength" rigging is right on the mark.

For an in depth discussion and info, check out a previous threads at http://bdsmlibrary.com/forums/showth...ght=suspension , http://bdsmlibrary.com/forums/showth...ght=suspension and http://bdsmlibrary.com/forums/showth...ght=suspension .

So take a little time to get the rigging up to snuff, particulary when dealing with a big person and concerte floors. Then you can enjoy the fruits of the labor for many days and nights to come.