I use this with a 3.5 hard drive as an external drive. Works beautifully and I put my work on it - then transfer to my laptop using the USB connection. Never have to unplug the drive, just use the USB to move the hard drive around. :)
It worked fine with a laptop 1TB spinner but I also tried it with several 3.5 inch spinners and it does not have enough power.
3.5 inch 10K 'cuda 1TB and 2TB 5400 and a 4TB 5400 - none of them would spin up. Not enough power.
I have the Sabrent EC-DFLT. I'm running a WD Black 5TB HDD in my adapter right now and its working fine. My adapter came with an external power supply. I've used it for Samsung SSD 750 EVO, Crucial MX200 and Samsdung 840 EVO 500GB as well.