Key, 4x25 mm 

In your instruction manual, this part appears on the parts list as:

Item No	Models
51	Grizzly G8689 Grizzly Mini Mill Micro-Mark 82573 MicroLux Mini Mill BusyBee CX605 Craftex Mini Mill Harbor Freight 44991 Central Machinery Mini Mill Northern Tool 49657 KLUTCH Mini Mill Homier 03947 Speedway Mini Mill Cummins 7877 Cummins Mini Mill Various X2-US-MT3 SIEG Mini Mill Various X2-US-R8 SIEG Mini Mill Bolton XJ-9510 Mini Mill Hare & Forbes HM-10 SIEG Mini Mill Princess Auto 8507667 Powerfist Mini Mill Travers Tools OT2213 OTMT Mini Mill Eastwood 32498 Mini Mill Penn Tool Co XJ-9510-1 Precise Mini Mill Clarke CMD300 Mini Mill Various X2L-US SIEG Mini Mill WEN 33013 WEN Mini Mill
99	Grizzly G0463 Grizzly Small Mill Harbor Freight 93885 Central Machinery Small Mill Various X3-US SIEG Small Mill Woodstock International M1110 Shop Fox Small Mill
A82	LittleMachineShop.com 5500 HiTorque Bench Mill Various SX2.7-US SIEG Bench Mill LittleMachineShop.com 5520 HiTorque Bench Mill LittleMachineShop.com 6500 HiTorque Bench Mill LittleMachineShop.com 5550 HiTorque Bench Mill Various SX2.7L-US SIEG Bench Mill LittleMachineShop.com 6550 HiTorque Bench Mill LittleMachineShop.com 6570 HiTorque Bench Mill

Click your model to see the complete parts list.