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A 180 mm version with Cooke f4.5 triple element objectives and double turret oculars providing 22.5x and 30x magnification was produced in minimal quantities by the Japanese military. The real fields are 2.6 and 2 degrees, respectively. Both the 150 mm and 180 mm instruments have Porro Il prism systems. The 60, 80, 105, 120 and several 150 mm instruments are collimated by adjustable eccentric objective rings. In other 150 mm and in the 180 mm models, collimation is achieved by prism adjustment. Without fixtures this can be, and usually is, a very tedious affair. The larger versions can be quite heavy. Depending on the design, the 120 mm can weigh from 30 to 50 pounds without mountings. The 150 mm can weigh 80 pounds and the 180 mm weigh upwards of 130 pounds. One hundred and thirty pounds is not in itself very heavy, but these instruments do not have many hand holds and the alarming possibility exists of dropping such a rare specimen.  Neither the 150 mm or 180 mm models were produced in inclined eyepiece versions.