A sputtering magnetron with a rotating cylindrical target and a stationary magnet assembly (22, 24*) is described, the magnet assembly (22, 24*) being adapted to produce an elongate plasma race-track on the surface of the target, the elongate race-track having substantially parallel tracks over a substantial portion of its length and being closed at each end by end portions (22′), wherein the spacing between the tracks of the race-track is increased locally to materially effect sputtering onto a substrate. The increase in spacing may be at the end portions or along the parallel track portion. The increase in spacing may provide more even erosion of the target beneath the end portions of the race-track, and provide more even coatings on the substrate.