This is the Hop-Up Engine Mount from Tamiya.
This works for the Tamiya TGX, TG-10, TGM-01 chassis cars.

FEATURES: Lighweight aluminum engine mount
Eight cooling fins efficiently dissipate motor heat

INCLUDES: Two engine mounts
Mount screws that mount engine to chassis
Four 3x12mm screws, washers
Instructions

REQUIRES: Installing on chassis and attaching motor to mounts

COMMENTS: Will work only for the Tamiya TG series chassis cars.