The Dewalt IMPACT READY power bit has a 1/4" hex shank and is made of S2 steel. Each bit is approximately 1" long. This set includes 6 sizes (4,6,8,10,12,14) plus a bit holder.
S2 tool steel has been hardened for excellent strength and impact resistance. It has a tough core that resists breaking under shock loads.
These are Dewalt bits that are kitted into a multi-size set. (The bit holder is not a Dewalt brand part).