Review on StarTech.Com 20Gbps Thunderbolt 3 Cable - 3.3Ft/1M - White - 4K 60Hz - Certified TB3 USB-C To USB-C Charger Cord W/ 100W Power Delivery (TBLT3MM1MW),20Gbps - White by Andre Stephens

The cable will not provide full Thunderbolt 3 speeds. I get an average read/write speed of around 30 MB/s. That is USB 2.0 speed! I almost sent my external hard drive back, because i thought that there was something wrong with the drive. But then I tried a different cable and I was able to get read/write speeds in the 180 MB/s range on the same drive. The product is NOT a thunderbolt 3 cable, its not even a Thunderbolt 1 cable. It is a USB 2 cable with "C" connectors on each end. The speed tests were run with CrystalDiskMark and a GLYPH BlackBox Pro USB 3.1 Gen 2 External Drive.