Canon Lenses Ef-S 55-250mm
What type of polarizing filter for Canon 18-55mm and 50-250mm?

I have a Canon 450D with two lenses: EF-S 18-55mm IS 1/3.5-5.6 and EF-S 55-250mm IS.What f/4.0-5.6 type of polarizing filter should I buy for them? Circular of linear? I prefer the linear because it is cheaper. The first lens has a diameter 58 mm, not sure about the second round, but I think the same. Please advise.

For a digital SLR that is not supposed to matter but I would like recommend circular. Linear polarizers can be mistaken for AF measurement systems and film SLR cameras (and some digital SLR models too, depending how to build the camera). Get a move and you're safe anyway.