White /Red/ Brown/ Black
These Kailh box switches have stems which are surrounded by a “box” which provides two functions.
First of all, it keeps liquids, dirt, and dust from getting into the switches. This is especially important when the keycaps are taken off of a board and the switches are left “naked” for a time.
Second of all, the surrounding “box” supports the stem during the keypress and therefore restricts the stem from any horizontal movement, or “wobble” when moving downwards and when the switch is fully depressed.