Lead & Steel Mil-Spec Lower Spring Kit w/ Grip Screw Black. Made from stainless & spring steel this LSK is great for completing a lower or keeping on hand in case a component goes down in the field. Weve ran our springs in Class 3 MGs with no problems whatsoever. Rest assured theyre quality Specifications for Lead & Steel Mil-Spec Lower Spring Kit w/ Grip Screw: Manufacturer: Lead & Steel Color: Black Fabric/Material: Steel Gun Make: AR Platform Weight: 2 oz Last Chance: Yes Package Contents: Lead & Steel L&S Mil Spec Lower Spring Kit W/Grip Screw Standard Grip Screw Lead & Steel 121919: Mil-Spec Lower Spring Kit w/ Grip Screw Black