ICY DOCK Full Metal 4-Bay 2.5" SAS/SATA HDD SSD Mobile Rack Enclosure for 5.25" Drive Bay with Fan Control - ToughArmor MB994SP-4SB-1 | High Performance Storage Solution for Servers, Workstations & Data Centers

Works like a charm. Solid metal design, good airflow above and below for each slot, and a single power connector for all four (separate SATA data cables, one sata-power cable).Being me, I took the thing apart. Five screws and the backplane comes off, one more and its circuit board can be taken out and examined. Totally trivial, very well seated and secured... notches into the frame... zero wiggle room (good!). I counted 9 capacitors on the power distribution bus so they didn't cut any corners there. Inserting an HDD did not glitch the power for the other drives that were already in. I give the backplane a big thumbs up for design and engineering.The drive bays are solid. Considering that we are cramming four 2.5" drives into a 5.25" enclosure, the design is very good. The bottom of each bay drops out a little to give the bottom of the drive a little space. The areas near the screw holes are flush, though, but it didn't seem to have any issues mounting the seagate HDDs I had without a plastic protector (clearance on the HDD drive mounts is about 1mm to the drive's circuit board).It is not screwless... requires four screws (flatheads are included). Two are round holes, two are oval. Not sure why they didn't use round for all four but the two round holes are near the connector side so the drive's connector is guaranteed to be properly aligned. Easycakes, and honestly you only need to use two screws (in the round holes nearest the connector) anyway.The fan is the only downside, being small and noisy, but I still give the device 5 stars for several reasons. First, they included a fan control switch (OFF, LOW, HIGH settings). Second, airflow looks good for all four slots. In terms of the fan control, no point ever using 'HIGH'. Just use LOW or OFF. The LOW setting is definitely audible which is unfortunate but there isn't a whole lot of room on the design side considering the fan has to fit the height. On the plus side, not only is there an 'OFF' position (if you have SSDs, you don't need the fan), but if the case itself has good airflow you can physically remove the fan with two simple screws to open it up and allow the case airflow to handle any cooling requirements. The fan's power able goes to a connector and just pulls off, so its easy to remove.In fact, if you really wanted to and didn't want the hot-swap, you could unscrew the whole backplane and just use it as four permanent slots. Silly I know, but the case is so well engineered that it has that flexibility if you wanted it.Fan tests, Four 1TB Seagate HDDs. Writing mean all four drives writing continuously for 20 minutes or so. Temperatures taken using SMART info (all four returned the same temp within +/- 1C):idle, low fan: 26CIdle, no fan: 27C (i.e. PC case fan only, no direct airflow)writing, high fan: 38Cwriting, low fan: 41Cwriting, no fan: 47C (i.e. PC case fan only, no direct airflow)So with all those features and easy modding, ICY gets 5 stars.ADDENDUM - I had one issue with the dock. On one of the machines I used longer screws to mount the dock in the bay. They turned out to be too long and infringed on the tray area, causing damage to one of the trays which I didn't realize until I tried to pull the tray out and couldn't. This was my own fault. So remember to use the low-profile screws that come with the unit... or at least make sure they don't infringe the bays.ADDENDUM2 - If you purchase your own 40mm fan you may not be able to use the LOW setting. Depending on the fan, it might not startup unless you use the HIGH setting. I still definitely recommend purchasing your own low-noise 40mm fan and not using the cheap noisy one that comes with the unit. You don't need much airflow to cool HDDs (and don't need any at all for SSDs), so find the quietest 40mm fan you can and you will be a happy camper.The only downside to the unit is having to screw the drives into the hot-swap trays... in particular, losing the screws for the trays you aren't using atm. I recommend storing the unused screws in their plastic bag IN one of the unused trays.-Matt