M1.6/M2/M2.5/M3/M4/M5/M6/M8/M10/M12/M14/M16/M20/M24/M25 Knurled Nut With Collar Thumb Knurling Nuts Knukles Tuercas Manual Adjustment Screws Moleteada Ecrou 304 Stainless steel Thru-hole DIN466 Factory wholesale