Cooler Master SK621 Bluetooth Keyboard Review

Computing Products Reviews
The Cooler Master SK621

Cooler Master releases a high-performance keyboard for gamers and writers on the go with the new SK621 Bluetooth.

What is It?

The Cooler Master SK621 is a 60% sized tenkeyless Bluetooth keyboard that can be connected and charged with a USB-C to full USB cable. It has low profile Cherry MX switches. The Sk621 also comes with 32-bit ARM Cortex processor to ensure that every keystroke is accurate and response is seamless. Along with the processor the SK621 uses N-Key Rollover technology to further boost its accuracy. The Sk621 also does not compromise on looks and customization with fully programmable RGB lighting and software to customize beyond the pre-sets that come built-in. Most importantly, the quality of the keys has not been compromised due to the new low profile Cherry MX keys, which will give a great response and long life to this tiny powerhouse keyboard.

Low Profile Cherry MX Keys, RGB lighting, and an off switch so you don’t waste power


Product Name SK621
Model Number SK-621-GKLR1-US
Switch Type Cherry MX RGB Low Profile Switch
Material Aluminum / Plastic
Color Gunmetal
Polling Rate 1000Hz
Response Rate 1ms / 1000Hz
MCU 32bit ARM Cortex M0
Onboard Memory 512KB
On-The-Fly System Yes, for Multi-media, Macro Recording and Lighting Control
Multi-media Keys Through Function Key (FN)
Cable USB Type-C Detachable & Braided
Software Support Yes, Through Portal
Wireless Connectivity Bluetooth 4.0
Connector Cable USB Type-C (Keyboard Side)
USB 2.0 Type A (Computer Side)
Cable Length 1.8m, Braided & Removable
Dimensions 293 x 103 x 29.2 mm (L*W*H)
Product Weight (Without Cable) 424g(0.934lbs)
Warranty 2 Years


I write and game on the go quite a bit as well as use a media computer in my living room, so I have spent years fiddling with a different portable keyboard that was wireless and could never come up with a solution that I was entirely happy with. Even the better keyboards from companies like Logitech always felt somewhat flimsy, and the keys were mushy and not very responsive. So when I saw that Cooler Master was putting out a Bluetooth keyboard with high-end switches, my ears perked up.

I reached out to them and awaited my SK621 in the mail. I had previously reviewed other Cooler Master keyboards, such as the CK552 which I am using to write this article, and have always been impressed with the quality of their products. When the SK621 showed up at my door, I was immediately impressed by the compactness and build of the keyboard. Cooler Master shipped the SK621 with a nice velvet pouch to carry it in. This is a nice addition, as I expect the SK621 will spend a great deal of time in my computer backpack as I take it to work, conventions, and trips.

The last few years I have been trying to jam a full-sized gaming keyboard into my backpack only to have about two inches of the keyboard sticking out of the top. When you add the laptop itself and a gaming mouse, it eats up a lot of space and puts all of the elements in danger. Taking all of that into consideration, when I pulled out the SK621 out I immediately felt a sigh of relief. I plugged it in and let it charge. While charging I tested out how it worked wired into my home media computer.

The first thing that hit me was how compact it was. The 60% size is something to get used to, especially if you are accustomed to large sprawling gaming keyboards. If you are a laptop or tablet user, the size is something you may already be accustomed to. It can be a bit tight, but not to the point of affecting the quality of use.

The keys themselves also feel different from the full-size Cooler Master Keyboards, as they feel a bit softer and have a shorter travel area. The keys still have a good click and release and are very responsive. I ran the software and played with some pre-sets and was very happy with the looks available to me. The pre-sets can be used with a hot-key on the keyboard itself and do not need the software to run. This is good if you are using the SK621 with your tablet or phone, which I intend to do. As a matter of fact, I grabbed my shoulder bag and found that the SK621 and my Galaxy tab fit comfortably inside, which means that it may be perfect for small trips and coffee shop excursions. This is another huge plus for me.

Now that it was charged and I already had my tablet out, I wanted to test the connectivity. There were no issues connecting the SK621 to my Galaxy tablet, Galaxy S9, or iPad, which was great. Once again, the responsiveness was fabulous and the feel was far superior to the previous Bluetooth and wireless keyboards I had used.


I feel the Cooler Master SK621 is the all-purpose wireless keyboard I have been waiting for. It is a compact, well built, well designed, customizable wireless keyboard that is suited for at home and on the go use. The SK621 is years ahead of any keyboard I have seen in this size range, and I assure you I will be taking it thousands of miles in the foreseeable future.

At $119, it is certainly not as cheap as the other mini Bluetooth keyboards on the market, but you also won’t have to keep buying a new one every six months as I have with the discount models. This is a keyboard that you should get years of hard work out of and for that reason I recommend it for anyone who feels that performance and portability is a priority when it comes to gaming or writing on the go.

A sample of the SK621 was made available by Cooler Master for this review.

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