Description

The  Extension Ring have  length of 4mm,5mm,6mm,7mm,8mm,9mm.10mm.15mm.20mm

Outer diameter: 60mm

pitch：0.75

male thread length: 3mm

4mm-female thread  length is 3mm

5mm-female thread length is 4mm

6mm-female thread length is 4.5mm

7mm-female thread length is 5.5mm

8mm-female thread length is 6mm

9mm-female thread length is 7mm

10-20 mm female thread length all is 8mm