I would like to commend the craftsmen that made the BUTLER! It really is a work of art! Fits perfectly on the back of my iMac. Nothing to install--just slide it on. I put a couple of backup SSDs, iPhone charger, and a CD drive on the back, and there's room for more. Very practical. As a side note, the customer service is top-notch. Nice folks and overall great company. Don't hesitate to purchase from them. I can't recommend them enough.