Phillips Pan Head SEMS Screws Machine Screws with Pre-Assembled External Tooth Lock Washers Machine screws with pre-assembled lock washers Features a free-spinning external tooth lock washer beneath the head Single part design saves time and hassle Excellent solution for bulk projects of production lines Zinc plated steel Phillips Pan Head SEMS with External Tooth Lock Washers are essentially a pre-assembled machine screw with lock washer. The lock washer is beneath the head of the screw and is free-spinning. This pre-assembly saves time and hassle on production lines and in any application where a machine screw with lock washer may be necessary, since they do not need to be put together, and there is no need to worry about losing a screw or washer. External Tooth SEMS screws provide greater torsional resistance than internal tooth lock washers. Because of the integrated lock washer, SEMS screws are often referred to as lock screws, or locking screws. Product Specifications: Product Type: SEMS Machine ScrewStandards Met: ASME B1.1, ASME B18.13, ASME B18.6.3 Material: SteelGrade: AISI 1022Finish: Zinc PlatedHead Style: PanHead Diameter: (Max 0.373 - Min 0.357)Head Height: (Max 0.133 - Min 0.122)Drive Style: PhillipsDrive Size: #2Thread Size: #10-24Thread Diameter Major: (Max 0.1890 - Min 0.1818) Thread Diameter Minor: (Max 0.1619 - Min 0.1586)Thread Pitch: 24 per inchThread Type: UNC (Coarse)Washer Type: External Tooth Lock WasherWasher Outside Diameter: (Max 0.381 - Min 0.365) Washer Thickness: (Max 0.024 - Min 0.018) Phillips Pan Head SEMS Screws - External Tooth Lock Washers Zinc Plated Steel SEMS screws in this selection are made from grade AISI 1022 Low Carbon Steel. The screws are then plated with zinc to add corrosion resistance, durability, and protection to each fastener. SEMS Screws SEMS Screws are essentially machine screws with pre-assembled washers. SEMS screws in this style feature an integrated, free-spinning external tooth lock washer designed to resist loosening of the screw due to vibration. Common Uses The value of a SEMS screw comes in time and hassle saved. Phillips pan head SEMS screws come with the lock washer already attached, which means no mismatched parts or creating a screw and washer assembly at the time of installation. For these time and hassle saving factors, SEMS screws are commonly seen in manufacturing, production and on large job sites.