This small object allows you to learn how to insert different depth M3 heat sert inserts. 

Through-holes and clossed-holes.

Depths:

• 4mm(for 3mm insert)

• 5mm(for 4mm insert)

• 6mm(for 5mm insert)

• 7mm(for 6mm insert)

• 9mm(for 8mm insert)

For closed holes it's recomended to have a 1mm deeper hole that's why there is 1mm more in each hole.