i would say that aluminum loops take off a full 10 fps is a little extreme. i also dont believe my rubber tubbing doesnt take off a full 10 fps. i would say the alum loop would take off about 7 and the peep tubing about 6. sims says their leeches only take off 2-3 fps. i believe this is true, i didnt notice any difference when i put them on my bow.