• Outer Diameter: 190mm
• Inner Diameter: 183mm
• Cross-Section: 3.5mm

You may be more familiar with silicone o-rings. We tested and researched o-rings made of NBR (nitrile rubber) and VMQ (silicone rubber). Both materials are excellent for different purposes – for gummy mounting, we found NBR to be superior.

Based on the findings above, here's why nitrile rubber beats out silicone rubber for gummy mounting:

• NBR has good tear strength and abrasion resistance. This was a top priority for us, since this mod involves stretching the o-ring to fit the keyboard. The o-ring then must withstand sustained pressure against multiple contact points. VMQ scored poorly in this regard.
• Compression set resistance is a measurement of how well a material can revert back to its natural shape after being compressed. This is important for reusability and durability. For compression set resistance, both materials are good, but NBR edges out VMQ.
• VMQ excels in resisting high temperatures. However, this is an irrelevant trait to gummy mounting, unless you plan on leaving your keyboard out for a suntan.

If other vendors offer 30A o-rings, they usually will have them in VMQ, since super soft NBR can be harder and more costly to manufacture.

30A has the approximate hardness of a mousepad or a rubber band. For comparison, the standard 50A has an approximate hardness of a pencil eraser or the inner tube of car tire.

A few years ago, we considered a rigid keyboard with zero flex to be superior. Nowadays, the enthusiast community is seeking a softer, bouncier typing experience. In the end, this all comes down to your preference, but we offer this 30A o-ring because we know people want it!

Gummy mounting is a type of gasket mounting that involves fitting a large o-ring around the PCB and plate, to provide a softer and bouncier typing experience. We highly recommend watching this video to see an example of how to perform this mod. Perform this mod at your own risk!