The Boss AB 2 is a two way selector pedal that allows you send your signal to two separate outputs or to send two inputs to a single output.  This is helpful for a number of reasons as you can send your guitar to two different amps or you can send two guitars to a single place like a tuner or specific pedal or amp.  I love having this pedal around as it comes in handy quite often, especially when I want to have quick access to two different amps.  The pedal has two 1/4 inch inputs/outputs labeled A and B and another two 1/4 inch connections that depending on the way you have set it up, will be either inputs or outputs.  The foot switch and LED lights are easy to use and understand, and overall the pedal is easy to bring around because of its light weight.  The pedal requires two AAA batteries and the pedal has true bypass so it won't change the color of your sound.  This is a huge feature because for me it is vital that my tone isn't affected negatively by the pedals that I am using because I often use a clean tone.  I haven't really used any pedals that are exactly like the AB 2, as the other AB boxes that I have used only have the option to go from one connection to two and having the configuration like the AB 2 opens up a whole new world of possibilities.  The price of the Boss AB 2 is quite reasonable as it is cheaper than most effects pedals out there while still maintaining a high level of quality.  I trust Boss to make top notch pedals and I would definitely say that they didn't miss their mark with this one.  Overall, the Boss AB 2 is a pedal worth checking out if you want to have more options in terms of routing for your instrument.