There are 2 different Schneider Componon-S 100mm f/5.6 lenses; the difference is the mounting threads on the rear. You'll need to verify which type you have: 39mm (Leica) Thread Mount, or 32.5mm thread mount. It's easiest to determine using the US Schneider Web Site & look at the pictures.

39mm mount: https://www.schneideroptics.com/ecom...D=176&IID=1977
32.5mm mount: https://www.schneideroptics.com/ecom...D=176&IID=1973

The front lens cap would be different for each.

If you got the 32.5mm mount, and it did not come with an adapter, it is available here: http://www.bhphotovideo.com/c/produc...ica_Mount.html

The front internal threads on the 39mm Leica mount are 43mm, so measure carefully. That's about 1/8 inch difference between the 2 sizes.

Schneider sells replacement lens caps--I'd call to make sure to get the right one; otherwise you could use a generic snap-in lens cap.

Also, if you want the detailed dimensions, you can go to the Schneider Kreuznach site and find a brochure that lists all the dimensions that are important. I didn't see that on the US site.

Charlie