How the Mechanical Keyboard O-Ring Modification Works

How the Mechanical Keyboard O-Ring Modification Works

By: Henz Llarves | Date Posted: May 25, 2022

How the Mechanical Keyboard O-Ring Modification Works

Continuing on from our Mechanical Keyboard switch guide, Mechanical Keyboard Info is back! This time with our new writer to help explain how O-rings work and how to use them.

One of the most common mechanical keyboard modifications mentioned is the O-ring mod. Mechanical Keyboard sound comes from 2 sources; the spring as it compresses, and the stem on the down-stroke and upstroke.

The solution? Modifying your keyboard with O-rings. These will help reduce the amount of noise each keystroke will make by removing the sound of the down-stroke.

Khali Box switches require a special 001 O-ring. The concept is comparable, but the ring is applied differently— inside the housing, the underside of the stem. Using O-rings on BOX switches requires quite a bit of tampering.

40A-R or 50A O-rings are the most common sizes for mechanical keyboards. The inside diameter should be ~4.5mm.

How the O-ring mod works

The O-ring will impede the stem of the switch from making contact with the bottom housing, and therefore inhibits noises made from bottoming out. This, however, leads to a permanently reduced travel distance.

The bottom of the O-ring cannot travel through the switch housing, nor can it move upwards due to the top of the keycap. It is therefore contained and squashed between the two parts.

ring prevents the stem of the keycap

The ring prevents the stem of the keycap from fully traveling down the switch.


Certain keycaps like SA or dev/tty MT3 will not work with a single O-ring, as the stems are too tall. The O-ring simply slides upwards freely on the stem as it is only facing resistance from the switch housing and not the keycap itself.

To overcome this, it is possible to use several O-rings in the keycap to “fill it up”.

It is important to note that with too many O-rings, sometimes the switch will not be able to actuate when pressed, as the stem is unable to travel enough to actuate the leaf.

DSA and SA keycap O-rings

The picture above is the comparison between the number of O-Rings required for a DSA and SA keycap.

Usage in the community

The feeling of O-rings is, like many things in the community, very subjective. Some despise the “mushiness” that the rings provide, while others claim to thoroughly enjoy the reduced travel and rubber cushioning.

With enough force on the down-stroke, key switches will still resonate some sound—described not as the usual “click,” but rather a softer drawn-out “thwomp.”

In my opinion, Linear switches benefit from the mod, more than tactile and clickies. Simply because there aren’t additional factors that contribute to the sound the switches make.

Close up of O-Rings on SA Keycap
How the Mechanical Keyboard O-Ring Modification Works

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