For sale as I'm clearing out my collection. This is a keyboard made by the manufacturer ZEOS, known overseas as the Space Invaders, and in Japan primarily as the NMB (hi-tek) black switch model. NMB mechanical keyboards often have large Bigfoot-like cases, but this one is about the same size as the standard RT6600 series. I used it for a few days, and then stored it in its box. The condition is good, with very little wear and yellowing, but there is some slight dirt on the cable (see image 6). I have confirmed that all keys work by using a PS/2 adapter cable. I didn't feel any problems while pressing the keys, but it's a keyboard from about 30 years ago, and although it's currently stored in a cool, dark place, there is a possibility of deterioration. Therefore, please purchase only if you understand this.