Old Soviet rare button unusual design with four contacts, in excellent working condition. The base and handles are made of bakelite, the contacts are made of steel. The button is very similar to a small telegraph key, but most likely it is a button, since it closes not one (like a telegraph key) but two contacts. Apparently this button was intended for some demonstration purposes, as it does not have mounting holes. Due to open contacts, it is best not to use it with high voltage. On the reverse side there is the name of the button or plant "KZF" and the inscription "Made in the USSR". The buttons are apparently new, they were with preservation grease. I washed it off with a solvent. This button works as follows: If you look from the side of two contacts (as in photo 5), then when you press the button, the central contact with the left contact closes first, and when you press further, the farthest 4th contact with the right contact closes. The price is for 1 pc. Size 3.8x2.5" / 98x63 mm