Viltrox EF-EOS M2 is a professional lens specially designed for EOS M, Focal length is multiplied by 0.71 based on the original (equivalent focal length = focal length x 0.71), which helps enlarge 1 level aperture.
If a lens intended for 35mm film or similarly-sized full-frame camera sensors is connected to a EF-M-mount camera, this adapter condenses the light from a lens designed for 35mm film or "full frame" camera sensors and projects it onto a EF-M-mount camera's APS-C sensor. This allows the APS-C sensor to utilize more of the light gathered by a connected lens, which effectively reduces the crop factor while making available to the sensor an additional one stop of light for each of the lens's f/stop settings.
Specifications
Model: VILTROX EF-EOS M2 Mount Adapter
Compatible lenses: EF series lenses
Focal Lenth Multiplier : 0.71x
Optical glasses: 4 groups, 4 glasses
Tripod Socket: Cu1/4"×1
Diameter and Length: 68mm×27mm
Weight: Approx. 145 g (excluding accessories)

Features:
USB Firmware Upgrading
0.71x Focal Reducer Booster
EXIF Info. Transmitting
Support Auto Focus Function
Electronic Aperture Control
Built-in IS Stabilization Function
Gold-plated Contact Pins for Great Conductivity
1/4 Bottom Tripod Base Plate
Aluminum Alloy made, powerful and stable
Compatibility:
-Compatible with EOS EF Mount lenses
-Compatible with EF-M Mount Mirrorless Camera:EOS M/ EOS M2/ EOS M3/ EOS M5/ EOS M6/ EOS M10/ EOS M50/ EOS M100
Notice:This adapter is not Compatible with EF-S/EF-M/CN-E mount lens!
Package:
1* VILTROX EF-EOS M2 adapter
1* Front cap
1* Rear cap