How the Mechanical Keyboard O-Ring Modification Works

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Mechanical keyboard switches with O-rings
O-rings on Cherry MX Clear switches. Photo by Tommy Thai

Brief overview written by Tommy Thai

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 special 001 O-ring. The concept is comparable, but the ring is applied differently— inside the housing, 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.

Switches With O-Ring Mods
O-Rings applied on multiple different keycap profiles

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 is contained and squashed between the two parts.

O-ring applied to the underside of a keycap

The ring prevents the stem of the keycap from fully travelling 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.

Comparison betwen the amount of O-Rings required for a DSA and SA keycap
Comparison betwen the amount 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,” rather a softer drawn out “thwomp.”

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

Close up of O-Rings on SA Keycap
Close up of O-Rings on SA Keycap

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