congrats on getting your oneleaf mars mt1000 640 .. i bought mine last november and really like it .. i want to pass along some information that i learned with my scope about the mars scopes , some have a bug in the firmware some dont , of the ones with the bug it does not cause an issue everytime .. the scope will always hold zero on base mag .. what the issue is when zoomed ocassionally the reticle will jump up and your shot will be about 18 inches high and when zoomed back to base mag it will return to zero .. oneleaf is aware of the problem and has released version 10 firmware that can be downloaded from their website .. install the "bug fix" firmware to resolve the problem .. my scope was version 9 firmware and had the problem , after the update to version 10 my scope works perfect .. good luck !