The great thing about the Cocoknits foam stitch stoppers is they slide all the way onto your needles (not just the tip) to hold your stitches. The stoppers can also be used to transform any double pointed or circular needle into a stitch holder. Love it. Love it. Love it.
The stitch stoppers are perfect for circular needles or interchangeable needle cords to keep stitches secure while trying on garments in progress. I really like that. They accommodate needle sizes 2-10mm (US0 to US15), and each pack contains four each of six sizes; 24 in total. If you like things neutral, they come in various shades of grey.