The pictured stem comes with thick shims for use with flat bars. In theory, you simply omit the spacers to use the stem with drop bars, but I have a couple of similar stems that are very slightly oversize for drop bars.
To fix the problem of slipping drop bars, I use aluminum foil as a very thin shim. Aluminum foil is great in that application because it both fills the gap and provides a non-slippery mating interface.
Last edited by Trakhak; 12-10-22 at 08:44 AM.