The cooler consists of a variable number of aluminum pressed plates forming oil ways and end tanks, the oil ways contain turbulators. These do not only break down boundary layer effects in the flow to obtain maximum heat dissipation without undue pressure drop but also, because they are brazed to both surfaces of the plates, hold them together under pressure. The oil ways are interspersed with aluminum strip louvered and formed into corrugations to provide airways.
Maximum working pressure on the standard range of coolers is 10 bar (150psi) although each cooler is tested to 11.5 bar (170psi) this is adequate for all but the most arduous motoring applications.
The coolers are available in various heights and two widths, 115mm matrix or 235mm matrix but only one, 51mm, front to back measurement. The height of a cooler is usually referred to in rows, these are the number of oil ways including top and bottom plates which carry oil.