This honing rod is oval and is coated with thousands of small industrial diamonds.

The diamond coated rod is 300 mm in length.

Handle in black plastic with rubber coating. 

A diamond honing rod is used to maintain the existing edge of your knife. Compared to a ceramic honing rod, this is much coarser and much faster. It brings back the sharpness in no time, but the edge is coarser and wont be as sharp as with the ceramic rod. It also eats up your edge faster. Its a quick fix no doubt. Its up to you to decide how you value time vs result.