There were no cylindrical lenses, so testing for astigmatism required the use of manual trial-lenses, for which there were rotating holders on the front of each eye hole, and there were stationary ones on the backs as well. Cross-cylinders were optional, but they did not flip like a Jackson cross cylinder, they rotated in the same plane, so they were probably meant for the near point cross-cylinder test for reading. It weighed 3 lb. 2 oz. Around 1920 an improved model, No. 574, was introduced, reduced in size but with the same range (lenses reduced from 1 inch to ¾ inch). The forehead rest was removed, and the rear trial lens clips were replaced with rubber eye guards. It weighed 2 lbs. 12 oz.