The Horizon Ultra is available in either a white or traditional black finish. Apart from personal preference in looks, the white finish is considered to be more resistant to tropical heat insofar as expansion and contraction are concerned.
The double prism lens is a beveled clear lens which is mounted as a sun shade and shows a discontinuity in the horizon if the sextant is not perpendicular to it. This lens can be readily introduced into the field of view, or stowed out of the way at the viewer’s option. This very nice feature, however, can only be used with a whole horizon mirror. A traditional split mirror would block half of the field of view and obscure the discontinuity, rendering it ineffective For this reason, the Horizon Ultra is normally recommended only with a whole horizon mirror, although a traditional split mirror may be installed in the existing frame later if desired. One sunshade in both the index and horizon array is polarized allowing for variable density if desired.
A distinctive feature of this model is a drum index corrector. This is a separate smaller knob that extends forward from the micrometer drum. Turning it allows the index error to be quickly corrected to zero by resetting the micrometer drum indication.
Included and Optional Equipment
The sextant comes with a 3.5 x 40 telescope and wooden case as standard equipment. Optional accessories include a 7×35 prism telescope, a Slip-on rubber eyecup for use while wearing glasses, and a Zero-magnification sight tube. A Practice bubble horizon and a Professional bubble horizon are available which facilitates effective practice without the need for a sea horizon.