These Stainless steel metal buttons are rugged , waterproof and look real good . Simply drill a 16 mm hole into any material up to 1/2" thick and you can fit these in place, there's even a rubber gasket to keep any water out of the enclosure. On the front of the button is a flat metal actuator, surrounded by a Blue plastic LED ring. On the back there are 3 contacts for the button (common, normally-open and normally-closed) and 2 for the Blue LED ring (+ and -). Connect 3 to 6V to the LED to have it light up nicely, there's a built in resistor! If you want to use this with a higher voltage, say 12V or 24V, simply add a 470 ohm resistor in series with the LED connection to keep the LED current at around 20mA.
This button is an on/off switch button, when you press it the 'normally-open' contact shorts to the common contact and the button stays 'pressed'. When you press it a second time, the button springs open, and the contacts open up again.

Technical Details:

Protection Level: IP67
Max. Current: 3 a
Max. Voltage: 250v
Material: stainless steel     
Shape:    HIGH FLAT round    (The actuator stays high out of the switch body in the non-pressed state)
Diameter: 16mm
Voltage: 3 a 250v
Function: on-off (Latching type)
Type:Anti-vandal type push button switch

Suitable for panel  height of 1U