This is a simple, lightweight device intended for crevasse rescue. It is made from the same 5mm polyester cord a the Micro-Prussik. One end has a 30cm loop, used to tie a prussik hitch on the rope, the other end has a 40cm loop, to put your foot in. Length can be 120cm-150cm.  I recommend you play around with a piece of string and the system you want to use this with to find the length, I probably can't advise you on it. 
 
End-to-end strenth is 8kn. A three-wrap prussik on all of the 6mm ropes that people have tried has always held body weight.