PC & Console Peripherals

Small, compact, but plays along with the big ones: The Cooler Master SK621

Those who don’t like the huge gaming keyboards, which have lots of extras besides the usual keys, usually switch to smaller keyboards, which only offer the bare essentials. The SK621 from Cooler Master shows that both RGB and Cherry MX Low Profile Red key switches can be installed in the smallest of spaces and that it doesn’t always have to be the chewing gum keyboard. The compact jewel also comes along wirelessly.

The SK621 seems to be an optimal solution for gamers who often have to clamp the keyboard under their arm or who have to be flexible with their setup. The Taiwanese company Cooler Master released the keyboard in the first half of 2019, shortly before its siblings SK630 and SK650 were launched. The three of them target different target groups as a series: The SK650 is the largest (with num-block), the SK630 the medium (without num-block) and the SK621 the smallest.

We took a closer look at the compact queen and can spoil it in advance: Cooler Master is still one of the best peripheral manufacturers on the gaming market, and rightly so.

Technical data

Key switch type Cherry MX Low Profile Red, mechanical
Material aluminum, plastic
Scanning rate 1000 Hz
Onboard memory 512 KB
Cable connection USB Type C
Wireless connection Bluetooth 4.0
Dimension 293 x 103 x 29.2 mm
Weight 424 g
Price € 70.93 *

60 % less is not less capacity

Cooler Master advertises the SK621 with a 60 percent space saving compared to a normal keyboard that still has Num-Block and Co. on board. We didn’t measure it exactly and calculated it, but that’s about right. And although the SK621 is really limited to the most necessary keys, it doesn’t need to hide itself in comparison to the big mechanical keyboards.

The famous mechanical MX Low Profile Red switches from Cherry are concealed under the flat double-shot buttons. These ensure that even the hottest battle is in the user’s favor, thanks to a key travel of 0.8 mm. The latter was further optimized for the Cooler Master SK621 from 1.2 mm downwards.

Keyboard with format and high quality workmanship

As you’d expect from Cooler Master, the smallest keyboard in the portfolio has also been given a brushed aluminum finish. The rest is surrounded by sturdy plastic, making the SK621 all in all robust and durable.

Weighing 424 grams and measuring 293 x 103 x 29.2 millimeters, the keyboard is pocket-sized and perfectly suited for commuters or e-sports enthusiasts who hurry from tournament to tournament.

Every keystroke is audible – not to be expected otherwise with the mechanical Cherry switches – but comparatively quiet. The keycaps have a high-quality feel and despite the small space between the keys, the Cooler Master is easy to operate.

You have the choice

The SK621 is a hybrid model and can be connected via Bluetooth 4.0 or a USB cable (type C), as well as all Cooler Master keyboards that have a 1 in the identification number.

If you decide to use it wirelessly, the internal rechargeable battery will give you something of the SK621 for four to five months, but only without RGB lighting. If you don’t want to do without it, the battery “only” lasts another 15 hours. But even these are sufficient for extended gaming action. And if you want to play longer than the 15 hours in a row, simply use the cable, which is anyway more delay-free. Unfortunately, the battery is not replaceable, so that after a few years you can certainly only use the cable.

Whether connected or wireless also decides how many keys can be used at once: While the cable version uses the N-Key Rollover technology, the battery mode registers a maximum of 6 keys.

RGB, so much space must be available

In true gaming style, the Cooler Master SK621 does not do without decent RGB lighting. Each button is individually illuminated. And yet it manages without RGB control via software.

The 18 illumination modes can be changed by key combinations with the ring button, which serves as a function key, as well as the colors. Macros can also be stored using the on-the-fly system. An onboard memory of 512 kB, corresponding to the size of the keyboard, is available for this purpose.

But if you are into software, this is also helpful: Cooler Master gives users the ability to use 16.7 million colors in the way they want.

Conclusion and price

Compact, like our test device itself, we kept the review of the Cooler Master SK621 compact. The reason: There’s not much to test with the small keyboard. But that’s exactly what it’s all about. In the end, the SK621’s few features are important for excellent performance and great added value. And the compact Cooler Master can do all this. From the switches to the RGB lighting and the format, the SK621 is an absolute gem. But it takes getting used to playing on such a small keyboard.

The Cooler Master SK621 is clearly aimed at users who need to be flexible and who also need to take their keyboard with them. We say: Cooler Master has achieved something very special with this mini-keyboard and we really don’t have anything to complain about.

Not even the price. Although the SK621 was introduced to the market at 139.99 euros, the compact queen of Cooler Master is now available at a lower price. Features, workmanship, and format make it all worth it.

Cooler Master SK621

Value for money


The Cooler Master SK621 combines excellent workmanship in a special format with cool extras. The price is absolutely reasonable.

Cooler Master SK621 Tastatur, schwarz Bluetooth 4.0 price comparison

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Simon Lüthje

I am co-founder of this blog and am very interested in everything that has to do with technology, but I also like to play games. I was born in Hamburg, but now I live in Bad Segeberg.

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