Here's two colors listed for no period Am Tel & Tel co. [095] CD 121s.

The toll on the left appears to be of Hemingray mfg, and has the same upper wire ridge shape, but a slightly rounder dome. The toll on the right is possibly of Denver mfg, though the general shape doesn't match that of a denver toll. My thinking is that it may also be of Hemingray mfg. It has a similar shape, though a slightly more rounded dome.