This is one of the little things that doesn't get mentioned very often so someone new to the wonderful world of vaping can get confused. 99.9% of the drip tips on the market will fit 99.9% of the toppers on the market right now. The end that goes into the topper should be the same size no matter which one you get. The hole in the center may be bigger on some of them and they come in all shapes, sizes, colors and materials (aluminum, stainless steel, ceramic, plastic just to name some of them).
I had the problem of not understanding the difference between 510 and ego threading when I first started. Such a simple thing once I figured it out

The little inside threading=510. the larger outside threading=ego