Buckling rubber sleeve
Provided by the ASK Keyboard Dictionary
Aka/also known as: buckling sleeve
A buckling rubber sleeve (or simply "buckling sleeve") is a type of rubber tactile element used in some keyswitch designs. Some may not distinguish it from a rubber dome, but buckling sleeves are distinct in that they are seldom used in a keyswitch design for actuation when rubber domes are typically used for such. Most buckling sleeve designs in fact sit on top of a keyboard assembly instead of residing inside, used to provide tactile feedback and a keycap return force only. Many are also not a complete dome shape and may appear to be a dome that is upside-down. Capacitive and membrane keyboard designs have made use of them, such as the tactile variant of Key Tronic "form-and-foil" and Mitsumi KPQ-series keyswitches respectively. "IBM buckling sleeves" is the provisional name for a major membrane-based keyswitch family that was used on many Model M family keyboards for the space-saving, point of sale and laptop markets (including many early IBM ThinkPad laptops) and seen as a high-quality alternative to the average rubber dome and scissor-switch keyswitch designs. Alongside IBM buckling springs, it's only one of two IBM-originated flagship keyswitch designs still in production.
