Editing MEI T-5 series (section)

==Design==
The switch contacts take the form of two turned metal terminals, around one of which a piece of sprung wire is pressed, with both ends facing away from the terminal. One end of this wire rests against the centre post, and the other rests against the second terminal. A loose plastic arm is dropped into the base of the switch; it appears that slider rotates this inwards away from the side of the switch, thus pushing the contacts apart. A small nub prevents the contact wire from riding over the top of this arm. The second end of the wire stops the whole wire from rotating around the terminal. The documentation indicates that the switch is specifically designed to allow the contacts to close under their own power, to reduce [[contact bounce]] and produce more consistent bounce times. Contact bounce is given as 4 ms maximum. The use of heavy terminals, together with the mounting studs, relieve the need to use a [[mounting plate]] to secure the switches, and indeed these switches are found [[PCB mount]]ed despite their size.

Travel is cited as 0.170±0.010&Prime;, around 4.3 mm. Pre-travel is cited as 0.080±0.030&Prime;, around 2 mm. Switch travel in the variants sold by RS is long at 5 mm, and the stem height for the keycap is 9.4 mm on the straight stem variants. The straight stem keycap mount is cruciform with a cross ca. 4.8 mm wide and arms ca. 1.2–1.3 mm thick. An illuminated version (T-5L) also exists. The shell is around 17.9 mm tall in total, and 15.8 mm square.

The switch is designed to provide two sets of contacts, allowing for SPST normally-open (NO), DPST NO and independent SPST NO + SPST NC; this last form can be wired up to produce a changeover switch. Latching action is catered for, as is illumination using a lamp that fits into a post in the centre of the switch, within the wide diameter [[return spring]].

The top of the switch is removed by pressing four corner clips in with a sharp implement. Although the top and the slider appear to be square, they are not; the top and slider have 180° rotational symmetry, not 90°. The holes in the sides of the slider correspond with the contact separator arms (with typically one present, for SPST configuration). The slider arrangement is documented as having "precision tracking surfaces" between the slider and shell, which "prevent binding even when double-width keytops are installed".