Hex plug gauge 2MM A/F, Hex. Plug Reversible double sided GO Gauge -2.023 to 2.025 A/F - GO Length 1.805 to 1.810, Nogo Length 1.995 to 2.000 mm (Required Check The HEX Slot For M4 Grub Screw F0101.2030.01, HPG2020.2080.1800.2000)