I love how the f75, f70, and t2 ballance with the battery box in the back under the arm cuff. Down side is when you set the detector down that part in particular is susceptible to water and dirt. I consider these elbow covers a must have for anyone that uses these detectors. It protects that important part of the detector from water and dirt. The fit is good and tight. Once aligned and on it isn't going to fall off. Good product! I have one on all my detectors now that have the rear battery box.
I may have ordered the wrong one. It will not fit my machine. I ordered the elbow assembly.