Here's a weird thing I've noticed: the made in China regular tapered ink caps are smaller than normal in each size and have a lump on the bottom from molding that makes them unstable and want to tip over, even when you slide them through some A&D to stick them to your set-up. Mine are manufactured in Pennsylvania, and the lump is much smaller. They're the same as the ones that I've always purchased for my own use through another reputable supply company. They come in the normal US pipe cap sizes that you're used to: #10, #16, and #22. They sit there just fine without spilling all your fucking ink everywhere.