Check the listing for details. Unknown Solid State Relays, Amplifier Preamp Cittra 9V 681 0068100210 Guitar New. Condition: Open box. Listed at 7.99 USD. 1374F8C.28 Some Kind of Electronic Devices, Possibly Solid State Relays, or Guitar Amplifiers, or Preamps, or Something; Part Number 0068100210, or 4572825, or 681, or 33240, or 06-12. Each bid quantity is for One (1) Unit. You may bid / buy any number, up to the total quantity available above. These were acquired at a salvage freight auction recently, and other than a few scuffs and scratches from being shipped in bulk, they are brand new. The practice at such auctions is to strip off all the box labels prior to sale. Thus, the only information remaining was the small white labels on the devices themselves, and the liquidator's auction description: "Para Cittra." We couldn't get any of the numbers to Google anything meaningful. The word "cittra" seems to mean some variety of guitar or stringed instrument. A couple of helpful eBayers have emailed us saying that these are some kind of solid state relays, so we'll go with that. The bodies are poured full of some kind of resinous substance, which is probably to secure the electronic components inside, and perhaps equalize the heat somewhat. I found two small holes in the top / flat surface which will accept about 3/16" of a straightened paper clip. Wouldn't recommend the paper clip thing after you have connected a battery, unless you know what you're doing. Here's what the labels say: 9 Vdc 50mA CSA (certification mark) C US 0068100210 S 06-12 33240 The following is molded into the housings: RV (followed by some kind of logo) 681 Overall length (including mounting ears): 4.000" Body length (excluding mounting ears): 3.223" Width: 1.770" Thickness: 1.192" Mounting holes: Accepts a #6 machine screw, spaced 3.600" OC (on centers) Connections: Appears to be a socket to put a 9V battery, plus (3) 1/8" male spade terminals