This wheel is from LadyQueen and contains six different fluorescent coloured studs. Of each colour there are both square studs and round studs. The square studs are 3mm and the round ones are 2mm.
Some nail accessories are overly 3D which makes wearing them a little difficult. These studs aren't huge and don't stick out too much and as such are easy to wear.
In the past I have been known to paint plain silver studs so that they were the colour I wanted, these studs mean I don't have to fiddle about painting tiny squares, waiting for them to dry before applying them. Also they come in fluorescent colours which I don't own in nail polish, so couldn't DIY myself.
To use these I just stick them to my nails while my top coat is still wet, you could use nail glue for a more secure fix. You can use top coat over the top of the studs to seal them in to the nail which will help them to last longer.
Below are some nail designs I have done using the studs, clearly I was feeling the summer when I used these studs!
Something neon orange and fluorescent pink;
China Glaze - Flip Flop Fantasy
Pink and Blue Neons;
Glamour by YOLI2UL - 825
Finally something much less neon;
Nails Inc - New York Noir
$2.70 - LadyQueen