The all-metal adapter is designed to fit the lens securely, yet can still be removed easily when not needed.
Feature:
It has a female 36 TPI (thread per inch) thread at one end, which will hold any microscope objective with a standard RMS (Royal Microscopy Society) thread.
At the other end, it has a standard male M42mmx1mm male thread to connect to your 42mm adapter.

Specifications
Material: Aluminum
Height Size: 5mm
Inside Thread: RMS
Outside Thread: 42mm X1mm
caliber：20mm
Compatible with:
RMS(Royal Microscopy Society) lens
M42 Mount

Package Include:
1x Lens Adapter Suit For RMS Royal Microscopy Society Lens to M42 Mount