I installed 19mm black Gorilla wheel locks on my car which rusted immediately. I've been looking for a viable replacement that would be affordable and keep them looking rust free for a while but to no avail. Luckily I stumbled upon these vinyl caps that hold my wheel locks in place and provide a nice clean finish. I originally bought the 19mm color grommets knowing they said they wouldn't fit spline nuts, but wanted to be sure. myself. As they said they will not fit 19mm spline nuts. (They fit standard 19mm nuts perfectly though). I was happy with the look of the caps so I changed them to the next size up, 21-23mm to see if they would fit the spline nuts. I received the cleat caps and they fit snugly into the Gorilla wheellocks. Make sure you seat it onto the nut until it bottoms out. So far I haven't lost any of the caps while driving. I bought a set of 25 so I could have an extra if I really only needed 20 in case they loosen or stretch. (Although I think in other reviews people either didn't put them on all the way, got the wrong size, or kept taking them off to allow them to stretch). I will update this if they come loose and fall off.