SanDisk Professional 4TB PRO-G40 SSD - Up to 3000MB/s, Thunderbolt 3 (40Gbps), USB-C (10Gbps), IP68 dust/Water Resistance, External Solid State Drive - SDPS31H-004T-GBCND

Purchase to use with my 2018 15" MacBook Pro, specifically for the Thunderbolt 3 transfer speeds (40Gbps). The drive has worked flawlessly for the past 18 months. I do a lot of astrophotography image processing (stacking hundreds of 60MB images at a time) using this drive, so throughput speed is important for me. The drive design is stylish and rugged, being in a rubberized aluminum case. It is small, light weight and obviously quiet. It was super easy to set up and use, 100% compatible with my MacBook. At 2TB, it provides plenty of capacity for working with my large photo files. This drive is not used for archiving my files, for that I use larger, slower HDDs. Overall this SSD is a great value for the price and I would definitely buy again.

Finally a portable SSD with Thunderbolt speeds! It really is three times faster than the USB 3.2 Gen 2 drive from SanDisk I bought just last year (and, for Mac, also three times faster than USB 3.2 Gen 2x2 drives since the Thunderbolt ports on Mac won't use the second lane at all).At times, plugging it directly into a Thunderbolt 4 port on an M2 Mac mini with the provided cable, it connected using USB 3.1 rather than Thunderbolt. I verified this by looking at the USB and Thunderbolt buses using System Report; also BlackMagic disk speed tests were much slower when this happened (700-800MB/s rather than 2400ish). I'm not sure if that flakiness is caused by the drive, the Mac mini, or the cable—but I'd guess it's the cable. Other times, it connected to the Thunderbolt bus as expected.Mostly I will have this connected to a Thunderbolt 4 hub that nets me two more Thunderbolt 4 ports. I've found that this setup, with otherwise base M2 but upgraded to 24GB RAM, plus the external TB4 ports and storage, is very cost effective for my needs. Note that there is no decrease in speeds having it connected to the hub vs. directly to the Mac.Update 1: Because this SSD (the 4TB version) is **both 50% faster and 15 times larger** than the internal SSD on my 256GB M2 Mac Mini, I have turned it into a bootable drive and am running macOS from it. No complaints! Upgrading the Mac Mini at time of purchase to 2TB (half the space!) internally would have cost a whopping $800 extra with Apple's pricing, and I'd have less space. Not to mention it's impossible to upgrade the internal storage after the fact. Setting up as a bootable drive was simple and painless for me. More benefits of the big, fast bootable drive include plenty of space for memory swapping at higher speeds than the internal SSD if I run out of RAM, plus being able to keep large cloud storage drives fully available offline (Apple's FileProvider forces many of them to live in a particular location on the same volume macOS is installed on, which was too small for them until I moved to this drive).Update 2: If you're looking for a Thunderbolt drive that's a lot faster than this, don't bother looking. Theoretical max data transfer speeds over Thunderbolt 3/4 are limited to something like 22 Gbps (maybe 24 Gbps for Thunderbolt 4?) which translates to 2750MB/sec for Thunderbolt 3. The rest of the 40 Gbps bandwidth of Thunderbolt is reserved for other things. With this drive, I've gotten around 2480MB/sec read and 2400MB/sec write in BlackMagic disk speed benchmarks, which is close enough to top speed that I've stopped looking at, say, external Thunderbolt SSD enclosures + NVMe SSD sticks to try to get faster speeds than this.

I bought this to use as a backup for my computer, as well as for music production. The thing is great when it works - it’s hella fast, and so freaking tiny. Unfortunately, the device is constantly, spontaneously “improperly ejected” from my computer. I get constant notifications/warnings. I’m using the provided cable. It should just work. It’s less than a month old. I reached out to customer support a week ago and haven’t heard anything yet - not even a “thanks for reaching out” email. It might be worth it to check out their competition. This thing is too expensive for this kind of performance and (lack of) customer service, and you’re probably buying this because you need something reliable that actually does the thing it says it should do.Update: It’s been two months and I still am having constant issues with the drive spontaneously disconnecting. I still have not heard back from customer service after reaching out to the emails provided on their website. I also just wanted to say that I’ve had the overheating issues others have mentioned when it does work. Sometimes it seems to decide to just stop working because it gets so hot (which is yet another way I lose work thanks to this thing). I’m so upset that I spent so much money on this and have lost hours/days of work because of the problems this thing has. I’m in the process of trying to jerry-rig a solution - I just spent ~$50 on different kinds of tapes and cables to try to see if that will solve the problems. I cannot caution against this thing enough. Save yourself the headaches and heartaches of losing valuable data and go with the Samsung version. It may cost more up front, but you’ll be saving yourself in more ways than you know.Update 4 months later: Still no word from “customer support”. None of the cables (or tape) I purchased to try instead of the included one solves the issue, which is how I know without a shadow of doubt it’s an issue with this joke of a product and not my computer. This has been the worst purchase I’ve made in probably a decade. I’m going to end up buying the Samsung one, so I’m just out $400 because I made the mistake of not purchasing this with a credit card that might have offered more purchase protection. I still cannot caution against this thing enough. Do not make my mistake. Spend your hard-earned money on something that’s actually worth what you’re spending.