For many aircraft, you often need to mount your motor away from the firewall to get the prop in the correct location. This is especially true for glow models that are being converted to electric power.
With this series of cage style motor mounts you can move the motor away from the firewall, providing the spacing needed to get the prop out in front of the cowl.
This mount is designed to hold motors in the 30mm to 35mm size that have hole spacings of 25mm and 25mm for the mounting screws, and up to 45mm in diameter. The complete dimensions are given in the drawing below.