As the number suggests, the ES-775 is an upgraded version of the ES-175(e.g., gold hardware, split block inlays, pickup moved closer to the neck, ebony knobs, etc.) perhaps somewhat akin to the L4, but with a laminated maple top (whereas the L4 has a solid spruce top). It was produced either 1990-1992 or 1990-1994 (sources differ somewhat).
Archtop.com has a very pretty specimen on offer at the moment for the price of 4,115 USD. And here is a very different one; different headstock, different tailpiece, and, of course, sunburst rather than natural. The price is also very different: 2,400 USD. And here are the user reviews.