Thornton steel string acoustic improv. I acquired this from a gentleman on the Acoustic Guitar Forum a couple of years back. This guitar was originally created as an acoustic Improv nylon and the owner requested Chuck convert it back to a steel string. Plays great sounds great. Relocation is motivating me to downsize. semi-hollowbody guitar with a piezo pickup that is designed for amplified performance without risk of the feedback sometimes occurring with standard acoustic guitars. The guitar has a 1 ¾” nut width, so it will feel familiar to acoustic players. And this particular guitar has a 50s style neck profile (full, but not a baseball bat) rather than Chuck’s standard lower profile neck.