This is a dash mounting bracket for use with the M5 Stack Rear Cover (
https://www.shapeways.com/product/SQ3KX6MUT/m5-stack-rear-cover?optionId=159619450&li=shops)
Requirements:
#6-32 x 7/16" Button Head Cap Screw
#6-32 Flat Washer
Part Number: 37-100-016_1.0.1