 Rather than being fitted "instead of" a synchronised weapon, the Foster-mounted Lewis in the S.E.5 was fitted "in addition".The two guns were normally used together, both being aimed through an Aldis sight, implying a degree of harmonization; but in some respects this arrangement was less than ideal.Replacement of the"hybrid" S.E.5 armament with twin guns (either two Vickers or two Foster mounted Lewis guns) was considered, but it was calculated that the centre section of the upper wing would have required reinforcement to cope with the recoil and vibration of two Lewis guns firing simultaneously.