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

Item No	Models
11	LittleMachineShop.com 3900 HiTorque Mini Mill Various SX2L-US SIEG Mini Mill
128	LittleMachineShop.com 3960 HiTorque Mini Mill LittleMachineShop.com 3990 HiTorque Mini Mill LittleMachineShop.com 4190 HiTorque Mini Mill Various SX2LF-US SIEG Mini Mill
25	LittleMachineShop.com 6450 HiTorque Mini Mill
98	BusyBee CX612 Craftex Mini Mill Micro-Mark 84630 MicroLux Mini Mill Various SX2-US SIEG Mini Mill

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