Do you sometimes transfer multiple memory cards at once? Do you also need a Thunderbolt dock that allows you to attach multiple peripherals to a computer with a single cable? Yes, I have Perfect product for you.
The Pro-Dock 4 is a Thunderbolt 3 dock with four empty bays that accept custom-shaped memory card readers that can be purchased separately. This “Pro-Reader“modules have a standard USB-C jack on the back allowing them to be used on their own, or can be slid into the dock for cable-free use. SanDisk currently sells CF, SD, all-in-one card readers, and MicroSD slots, CFast reader, CFexpress Type B reader and Mini-Mag reader. 
The pier itself is full of gates. On the back you get two Thunderbolt ports, one DisplayPort, and one Ethernet port, and on the front it has a headphone jack, two USB-C ports, and two USB-A ports. 
I love using dual monitors with my home setup, and I was disappointed that the dock only had a single DisplayPort option. Luckily, I was able to use a USB-C-to-HDMI cable to get my second monitor up and running. Interestingly, this cable does not work with the front USB-C ports but works with the Thunderbolt port on the rear.
I’ve been using the Pro Dock 4 with my MacBook Pro M1 for about a month now and it works flawlessly. The only thing that keeps me from recommending this product to everyone is that very few people need four card readers, and if you don’t have one, $499 for a Thunderbolt dock is a hefty price to pay. 
I hope that SanDisk will add two more accessories in the future. First, they need to sell a USB-C expansion module for unused memory card ports. For those of us who don’t need to use all four slots for the card reader, having an extra USB-C port on the front would be great, but for now, the USB-C ports are too much. far to access.
Finally, SanDisk needs to sell an SSD memory module that can replace the memory card reader. Not everyone needs four memory card readers, but almost everyone who works on a laptop needs more memory. Of course, SanDisk makes a lot of solid-state memory, and I find it odd that they don’t currently sell additional memory modules for this dock.
With these two extras, I think this will clearly be the best Thunderbolt dock currently on the market, but for now, Pro-Dock 4 is the best Thunderbolt dock if you also need to transfer multiple memory cards at once.
