Pretty self explanatory here. Nice little old-school PG piece from when they made things in USA. I gained about .7dB using more pre-amp and less gain on a couple Zenon amps a few years back. It's been gathering dust since I got Zed Ra for pre-amp duty. I'm not promising gains, just saying what I found. Definitely adequate to jump up line voltage from 2V head unit.
Top pops off with just a flat head screwdriver to access gain pots internally.
30$ shipped in USA 40$ shipped outside USA.