riddle me this, 3/8" is approx 10mm, 1/2" is approx 12mm yeh? so why are fuel pumps im looking at list the inlet diameter as 12mm (3/8") and 15mm (1/2"). it just doesnt make sense and its hurting my brain. explain it to me, what am i missing, why the different sizes? http://www.bosch.com.au/content/language1/downloads/fuelpumps.pdf bosch pdf link for anyone who doesnt believe me.