They have an SDS Plus shank and a brazed carbide cross point that leads to four flutes. I've used a few - they work well as I expected. The bits are stamped in metric sizes, but for the most part can be used as SAE equivalents - rotary hammers are not precision tools. d Note that the smallest pieces have very little or apparently no relief behind the apex; There is no marked trail to clear debris and the pit is likely a bit sloppy as a result. However, on the few test holes I did, I didn't have any noticeable problems. I would say this is a good price considering the quality and range. I've used the standard SDS-Plus bit set I bought from Harbor Freight for years with nothing but success, so I can't say paying your nose for the highest quality tool is enough for something like this.