This tool is used to prevent the crankshaft rear oil seal from damage when installing it. It is very easy to damage oil seal without using this tool. OEM no.ref: 9990166 88800619 Application: FM12 D12 D13 Use this tool for 7" Crank Seal 85108352 Use this tool AND 88800619 for 7" Crank Seal 22191895 Use this tool, 9998238 or AM-9998238 for 7" Crank Seal 1543896 Use 9998238 or AM-9998238 for 7" Crank Seal 20441481 Use 88800561 or AM-88800561 for 6" Crank Seal 20441697 This is a high-quality aftermarket product. For D11 engine , you will need another seal tool.