Bondtech M3 Thread Insert 

Thread insert for applications when a metal thread is needed with plastic parts. Sold in units of 1. 

Insert Length: 5.2mm

Recommended hole diameter: 4mm

To attach the thread in plastic, a hole is required in the correct size for the selected insert.

Insert the thread insert into plastic with heat. The easiest is to make a special tip for a soldering iron and use it to heat up and fit the insert into the plastic.