I "shot" the Mark 25 Deluxe here in March 24 for under €400. It came in a simple plastic box with an incredibly poor opening mechanism. The sextant is made entirely of plastic and is very light. The telescope could not be focused at first because there is a rubber on the eyepiece that prevented it from focusing. It is also possible to use a tube without lenses at the beginning, which is included. The index mirror and index error errors are easy to study. The telescope should be pushed all the way forward in its holder to avoid stray light. My crew and I achieved remarkably accurate measurement results. On average, 2-3 nm of the line of sight from the GPS point. The index error must be determined or corrected before each measurement. This is no different with premium products. From my current experience, sextants with index correction and eye level correction are total nonsense. The Mark25 Deluxe has a full-view mirror and competes with the very expensive ones. There are also different colored filters for index and horizon, which Bremerhaven competitors do not offer. Conclusion: recommended and pay attention to the good price.