Are these not 280 mm calipers ?.

[gasketface]

I thought 288mm calipers had the diamond shaped hole in the top ?.Like those in the 1st link below

http://cgi.ebay.co.uk/VW-Golf-288mm-VR6-calipers-and-carriers-pair-/110691562227?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item19c5bb32f3

http://cgi.ebay.co.uk/VW-Mk3-Golf-VR6-front-brake-calipers-and-carriers-288mm-/260789746556?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3cb847bb7c