what is this fuel pump

hi i recieved my new fuel pump and fitted it today which was the bosch r11 pump suitable for 200 bhp , when i compared the new pump with the one i already had fitted i noticed the old pump was alot bigger than the new pump, does this mean it would flow more fuel? or does the size not matter, my old pump has these numbers and letters on it


E R S T K L A S S I G 1 8 3 6 9


does anyone know if this is a standard pump or already an uprated one, is it as good as my new bosch 1??? and what would it be worth to sell??? thanks