Electric guitar effects simple question?

Question

what is the name of the small box that you push a pedal and it changes the sound of the output on the amp? it says A1 all the way to E6 as u push the pedal?

Answer 1

  Try  this , BOSS  guitar effect  guide  books,they  have  a  website  if  you  are  interested  or  just  ....guitar  effects......................

there  is  so  many

Answer 2

could be any effect pedel, the a1 - e6 is just degree of effect. Whats the sound? Could be a phazer, compressor, wah wah..........