The Wiha 28171 drive-Loc VI nut driver blade with a size of 5.5mm. The blades are made of high-performance CRM-72 tool steel. It is through hardened hard chromed for maximum durability. Wiha Drive-Loc VI Nut Driver Blades are designed to work with Wiha Drive-Loc VI handles. When inserted, the nut drivers are adjustable in length and lock into place. Select a length from 1.7" to 4.8" in 1/8" increments. The Nut Driver blades are made of premium quality tool steel for strength and durability. Experience the tightest fitting machined driver tips from the company that set the standard for precision. Wiha's exact-fit tips meet the highest tolerances of precision machining to eliminate fastener damage.