sometimes the same pads fit a range of different sized discs, with different pr codes, and sometimes even different brands of cars.
eg. 1KW pads are also used with pr codes 1KZ,1KE,1KF,1KU, 1KJ,2EA.
as to why, the pr code relates to a brake disc and pad combo. if one car uses 288mm, and another 300mm, but both have the same pad they need to use different pr codes to make it clear which combo is being used.
it requires the use of 3 sites, because eurocarparts site is terrible (which reminds me of something im gonna mention later).
euros do not list pr codes clearly (although they do usually mention them in additional info). they also do not list either the OE part number nor the aftermarket part number.
that means you have to hope they have the pr code listed, or find the size of the brakes you need.
to do that, i use etka
https://audi.7zap.com/en/rdw/ to find the part numbers and basic sizes.
using the part number, you can go to a site like autodoc.co.uk, paste in the OE part number and get every part they sell which matches. you get detailed size info, aftermarket part numbers etc.
using the size info you go back to euros and match them up.
euros use your reg to get the basic info on your car, then offer options based on that limited info. eg. a4 2013 diesel. there might have been 3 brake options for that model, that year and that engine. they offer all of them and leave it to you to work it out. **** site.
speaking of autodoc.co.uk, i priced up the exact same parts (brembo) on their site, and came to £214.73 delivered. using a (pre-vat) 10% discount on topcashback, would get you back £17.90 for a total of £193.25 delivered, saving £44.22 over euros.
dunno if you need the parts asap, but if not have a read of
https://www.audi-sport.net/xf/threads/autodoc-review.386198/ and give it a thought
