Retaining Ring These screwdriver bits have a collar that acts as a stopper, preventing the bit from following the screw head into the drywall. The depth stop design can limit screw penetration and damage the panel, once the collar contacts the plasterboard the drill bit cannot advance. PH2 Screwdriver Manufactured Made of high strength S2 alloy steel, these screwdriver bits are very durable. Heat treated to resist breakage and wear, impact resistant tool steel for maximum durability with a 1/4 hex shank for use in bit holders. Magnetic head These bits of screwdrivers are with magnetic head, so they can fix firmly on the screw. Strong magnetic, can easily suck screws when used. The bright color of the retaining ring allows you to observe clearly and easily, which is helpful for your work. Widely used These screwdriver bits have a wide range of applications, with a hex shank of 1 /4 inch, designed to fit any electric drill and cordless drill for normal use. Note: The data are all manually measured, please allow 1-3cm error, due to the difference in light and display, there will be a certain color difference, the actual object received shall prevail. Note: The product may have a slight tolerance of 1-3 mm/1-3 g in size/weight, and the image color may differ from the actual item due to lighting.