Which headset bearibgs

[jarushby]

I wonder if someone can help me identify the spec of the bearing that I will need to replace the headset bearings on my trek 1200 (2005 ish I think)

The headset currently on the bike has the following info :-

"Aheadset"

"Manufactured by IP for Cane Creek , VP-A77C"

I am looking at a set of bearings on wiggle for £11.69 cane headset bearings but do not know what size I need

Any help greatly appreciated