#4-40 x 1/2" Slotted Drive Round Head Zinc Finish Steel Machine Screw / THREAD CLASS: 2A THREAD DIRECTION: RIGHT-HAND THREAD LENGTH: 0.450 INCHES MINIMUM AND 0.500 INCHES MAXIMUM FASTENER LENGTH: 0.500 INCHES NOMINAL HEAD STYLE: A28 ROUND HEAD DIAMETER: 0.193 INCHES MINIMUM AND 0.211 INCHES MAXIMUM HEAD HEIGHT: 0.075 INCHES MINIMUM AND 0.086 INCHES MAXIMUM INTERNAL DRIVE STYLE: B10 SLOT NOMINAL THREAD DIAMETER: 0.112 INCHES THREAD QUANTITY PER INCH: 40 SCREW MATERIAL: STEEL SCREW SURFACE TREATMENT: CHROMATE ZINC THREAD SERIES DESIGNATOR: UNC