Hα region of 18 of the 20 the double-lined systems detected in the survey. Each system shown displays two Hα cores; the two systems excluded, WD 0128−387 and WD 1115+166, are DABs and show only a single component at Hα. The figure shows one observed spectrum for each binary along with the best fitting model spectrum (blue smooth line). The observed spectra were smoothed with a Gaussian with 0.15 Å for display. Δλ is the wavelength offset relative to the laboratory wavelength of Hα.