Mechanical Enterprises Microtype MT-1
The photos below are archived from now-deleted eBay listing 122438774261 “Retro Vintage Microtype Mechanical Enterprises Inc. MT-1 Keyboard Unique Layout” by user gwzcomps of store Happycow Computing. They depict a Mechanical Enterprises Microtype keyboard, model MT-1, form MIRU (M = desk form factor, other letters uncertain).
The serial number is 06-0467-I10. There is no presently-known indication of the date of manufacture.