The Monsanto 101B is a compact frequency counter-timer. It comes in a metal case with a tilt stand for bench use. Its display has Burroughs B-5750 nixies. It uses TTL for the digital circuitry.
I bought this counter in spring 2004 through Internet. The person who sold it was a radio amateur who didn't use the counter any more. He didn't know whether it still functioned.
When I tried it, counter did work, but the range switches seemed to be a bit unreliable and the readings were not exact. I will have to invest some time to make this counter work again. This will be worth the trouble, I trust. It is a nice and compact counter, not too large like the other nixie frequency counters I have.