You're changing the rear only? Assuming you don't have ABS (you didn't specify your model year, so I can't know that), be sure you don't pick a pad composition that has much more "bite" than the fronts. There are some aftermarket brands that are more performance oriented, so you might fall into this trap.

The reason is a safety concern. TUV (Europe's version of the U.S.'s DOT or NHTSA) standards require front/rear brake balance (on all pre-ABS cars) so that the front brakes lock up under all conditions before the rears -- this ensures that the car stays straight when stopping.
Given that the 240's front brakes have more swept area than the rears, this would be preserved when the front and rears have the same brake pad composition, but it's possible (perhaps?) that a really high performance set of pads in the rear would make up for this difference, especially if you have a "cheapie" set of front pads (e.g., from NAPA, which laughably guarantees their pads for the life of the car, actually telling you that their pads really don't "bite" all that well) -- you don't want that!

Bottom line: it's always a good idea to have the same pad composition at all four corners, just as you always want to have the same type of tire (e.g., snow tires) at all four corners.

Just to play it safe!