Hi: Dink floats come in three sizes the smallest is about3/8"diam 6"length This float handles up to 1/2 oz of lead.When the float is properly weighted and set for depth it should drift downstream with about 2" above the water at an angle of 30deg off the vertical. If it rides any deeper it is hard to judge the angle. This angle means that your bait or lure is just sliding along the bottom in the fish zone. If the float rides vertical it needs to be slid up on the line to lengthen th distance to your lure. If the float rides at too flat an angle it means your bait is dragging too much on the bottom and is likely to hang up.
Other sizes of dink float will handle 3/4oz and 1/12oz of lead. Choice of weight depends on your equipment and on the current speeds of the water you fish. Its worth reading Dave Vedder`s information on the John site .