The sextant consists of circular anodized brass plates with a lid with bayonet fitting that when attached to the back of the instrument serves as the handle. The index arm is moved by a milled knob on the upper plate. The instrument has no shades. The index glass is non-adjustable and the horizon glass is moved by a milled key shipped in the upper plate. The lid has a small brass handle on the back, and contains a paper table for natural tangents to the power of 100.

Attached to the sextant is a single lens magnifier on a hinged 39mm swivelling arm. There is no telescope. It has a sliding pinhole sight with a choice of small plain glass or a larger pinhole. The sextant is contained in a fitted leather case lined with red velvet, and stamped on the side, ‘W.A.U.’.

The instrument has an inlaid silver scale from -5° to 155° by 30 arcminutes, measuring to 120° (the digits are read from the pivot). The sextant has a silver vernier measuring to 1 arcminute, with zero at the left.