This is a small momentary push button that I include one with the purchase of a door bell. If additional buttons are needed this is the same small button. It has a 10" wire lead, black and red, attached for connection to the doorbell pcb control board but can be used as a simple momentary switch for other uses. You may want to look at item 912 as an alternative. 912 is slightly bigger and has a red colored button.
Measurements: 3.18mm x 4.2mm x 2.55mm