Kleartone mouthpieces aren't too common and from the research I've done, it seems as though these mouthpieces were relatively commonly included in various American stencil horns. The most common are the pieces made out of white plastic material that resembled Brilhart's tonalin mouthpieces. This mouthpiece is internally similar to a tonalin mouthpiece with straight sidewalls and a slight rollover baffle. 

This mouthpiece is in excellent condition and features a .060" tip opening.

No cap or ligature included