This is for (100) pieces of Deck Screws Bugle Head Type 17 Square Drive. These deck screws feature a Robertson Drive, also known as a Square, or Scrulox drive. This has a square shaped socket in the screw head. This is to enable high torque and minimal slippage while using the screws. Since wood decks have many thin planks and must withstand harsh environmental conditions, these deck screws are designed to accommodate the challenges of this application. Deck screws must resist corrosion, drive easily, and lay smoothly against the deck surface, called countersinking. For these reasons, many deck screws are self-countersinking, self-drilling, and coated with materials that won't rust. Deck screws come in a wide variety of lengths and widths, called shanks. A popular head shape is a square because it holds the driver and doesn't strip as easily as Phillips heads. One feature of deck screws that makes them easy to install is the sharpness of their point. They often come to a very sharp, narrow point, to reduce the necessity of drilling pilot holes. The deck screw drives easily into deck boards, and once set, the head lays smoothly against the deck surface. The thread of the screw is measured in degrees, so a shallower degree means more thread along the length. These threads spread out the force, so the screw takes less effort to put in, yet it is still difficult to pull out. AISI 316 stainless is a premium grade of stainless and is considered by many to be best in class. 316 stainless is corrosion resistant and very durable even in the harshest of conditions.