The V810 is pretty much an exact circuit copy of the old TS808 Tubescreamer.  These were built in the 90's (no longer made) with very nice components, including Nichicon capacitors (that's what I use in my mods).  I did two tweaks with this.  I installed an IC socket so you can try different opamps to see what sound you like the best.  These come stock with an RC4558 (like the old Tubescreamers).  I have put a Burr-Brown OPA2134 in the socket for a slightly different voicing, but include the original (wrapped up securely in the battery compartment).  I also upgraded the cheap diodes in the clipping section for nice and better defined notes when in full overdrive.  Warm tone with that tube driven sound.  Excellent condition with no velcro on the bottom.