Back draw end mill extension holder, you can get higher precision:
1.BLC20-150L, front diameter 14mm, shank diameter 20mm,
2.BLC16-150L, front diameter 14.8mm, shank diameter 16mm,
3.BLC12-100L, front diameter 12mm, shank diameter 12mm,
They are used for 3mm, 4mm, 6mm carbide end mills
These extension holder can load different collet SDC6-3 , SDC6-4, SDC6-6 for 3mm diameter, 4mm diameter and 6mm diameter carbide end mill.