The Ultralight Strike Indicator is indeed ultralight. It is 5mm long - about 5/16" by not quite 1/4" wide. It floats, but is so small it will not support any weight. I am sure it was designed to be used when fishing unweighted wet flies. It will probably work when micro fishing or ultralight worm fishing with a small hook, small bait and no split shot.
I had imported them thinking they would make good microfishing floats, but when I realized they would not support even one size 10 split shot, I completely lost interest and never put them on the website. Recently, there was a discussion in one of the Your Stories threads about using floats and I mentioned them - which led to a request to put them on the website for the "crazy ultralight guys."
So here they are! Each package contains six hard plastic strike indicators, and six plastic toothpick-like pegs.
Slide your tippet through the hole in the middle of the indicator and then insert the peg to hold the indicator in place.
Because they are so light (.004 oz) and are relatively aerodynamic, they should not affect your cast much.