Kailh switch is a Cherry MX compatible switch, made by Chinese company “Kaihua Electronics Co., Ltd.”. (凯华).
Kaihua makes many types of switches, for keyboard, mouse, and other industrial applications.
Kailh Traditional (KT) Switches
The most common one is what they call Traditional Switch (KT) for keyboard. These are Cherry MX compatible switches.
Kailh KT Switch Spec
Note, Kailh Red has 50g force, while Cherry MX Red is 45g. That's a very noticeable difference. I know because i use Cherry MX red (45g) in X-Bows Keyboard and Kailh red (50g) in Ultimate Hacking Keyboard . I much prefer the lighter ones.
Kailh Box Switch
Kailh Box Switches are improved Cherry MX compatible switches.
Kailh Choc Switch
Kailh Choc is new low-profile switches.
Kailh vs Cherry MX
Keyboards Using Kailh KT Switches
Here's a sample list of keyboards using KT switch.
Truly Ergonomic Keyboard, Steelseries, Mad Catz, and others.
The following are just list of early adopters from 2015.