SparkFun Metal Pushbutton - Latching (16mm, Green) Buttons/Switches Turn Signal Assemblies & Lenses In other words

In other words

FTDI Basic Programmer or even combine it with the CP210x IC and SMD Mini-B connector to create your own portable USB device

USB power and RX/TX lines broken out to a 0

can be ground-referenced as well

die-cast enclosure is rated IP54 against dust and splashing water

SparkFun Metal Pushbutton - Latching (16mm, Green) Buttons/Switches Turn Signal Assemblies & Lenses In other wordsThis is a perfect choice if you are in need of a heavy duty push button! These metal push buttons are a very tough, small, panel mount latching switch with an illuminated green LED ring. It is a SPDT with 16mm threading and 1mm pitch. This button is perfect for basic On Off functions. Overall length (including leads) is 1. 5" and has small solder lugs for connection. These latched buttons are rated up to 3A and 250VAC while the LED is rated for 5 12V.