I bought the mount from Shapeways for my specialized power saddle to carry my Garmin RCT715.

(https://www.shapeways.com/product/SP88CTNWN/specialized-swat-garmin-rct715-mount-adapter?etId=203275774&utm_source=automated-contact&utm_medium=email&utm_campaign=payment-received&utm_content=7&option=266973615)

The RCT715 mounting hardware is from the Garmin RCT715 mounting kit so stock OEM from Garmin.

This mount is awesome, and I'm selling it because I'm switching back to the RCT515 and hence no longer need it.

The mount from Shapeways was $37, and the garmin mounting hardware kit was around $25.