Maybe there should be a warning here that this reducer does not fit the older version of Esprit 150 (I have tried and it does not fit into the draw tube) but it fits well in my newer Esprit 150. Maybe SW has changed the design or made some adapter since I bought mine, but anyone with an old Esprit 150 should check this with FLO. See this SGL thread: https://stargazerslounge.com/topic/366049-new-sky-watcher-077x-reducers-for-esprit-120-150/page/2/

I purchased this to bring the FOV using a KAF 8300 CCD camera more in line with my existing APS-C CMOS camera. No supplied documentation in the box but all the info you need is in the FLO description. Spacing is critical to achieve good star shapes in the corners, but one bonus is that focus is achieved with only 16 mm of focus travel, vs 65 mm when using the SW F/F. The stars in my OAG camera are now elongated but PHD guides on them OK and that may just require some adjustment of the prism.
A cheaper alternative to buying another IMX 571 sensor camera, recommended.