I got my first Panasonic CGR18650CH 2250mah 18650 battery delivered today. It fits in the ZMax better than the eFest IMR 2000mah 18650 battery. It is actually about 1mm or so shorter than the eFest so there is less pressure on the end capand the end cap screws on much more easily (no more fighting the threads to get the end cap on). I hope the battery works well for me as others have said it does. If it meets my expectations I will buy some more and they will be my main batteries for my ZMax. Tonight when removing the eFest I had the issue where the end cap pushed up on the eFest label. Like others, I had to remove it and move it higher up on the battery so it doesn't interfere with the end cap.