Edit after 2 weeks of use. See below dashed line for my first impressions.Will be absolutely returning.I might have kept it as a backup mouse just for change of hand position from my other ergonomic mouse, but the issues that reared their ugly heads make this unit essentially defective from a driver stand point:-Drivers in windows 7 install but won't run since windows gives the warning that the drivers are unsigned and won't be used for security reasons. The default windows drivers stopped working as well after installing the Windows 7 drivers from the contour website. So no way to customize buttons.-Windows 10 drivers seamed to work at first, but then the scroll wheel would constantly stop responding. Unplugging the USB dongle or pressing the "reset to default" button in the Contour software would get it going again, but only for a few minutes.So while I don't like the mouse from a comfort perspective, these defects in manufacturing and driver support are deal breakers. Very disappointing for a small company who you would expect a more reliable experience and better customer service from.-------------------------------------------------------------------------------------------------------First impressions. Ill try and remember to update after some trial use:Generally, Cons out-way the prosHand size: man (smaller size - see photos)Sorry for caps. Just replacing bold for emphasis.CONS:-NEEDS MORE PALM SUPPORT: Always twisting palm to rest on back end of mouse, which defeats the purpose of an ergonomic mouse to keep with wrist in a neutral position.-FRAGILE THUMB REST: Needed to buy extended warranty to guard against thumb rest breaking based on other comments.-DIFFICULT TO MAKE SMALL ADJUSTMENTS: An easier glide with a stop lock would be a better design than friction lock in my opinion. Unless a stop design would be more prone to failure/breaking.-SCROLL WHEEL ON THE THUMP POSITION: in my opinion and experience, this is what causes a large amount of arm and back issues. Constant use of the middle finger to scroll. I would have it in both locations like the logitech ergonomic mouse and be able to use both for vertical scroll to allow relaxing one digit occasionally.-SIZE AND PLACEMENT OF "MIDDLE" BUTTON: I feel we are all used to middle button on the scroll wheel now and this is confusing. I like the idea of a middle button, and understand why it's not in the mouse wheel on a vertical mouse, but I would either put it near the thumb or switch the location with the right click button. The current middle button location isn't something many of us have used for 20 years, and it's confusing since on current mice, this is where the right click button now sits in relation to the scroll wheel. Hopefully the drivers allow reversing the middle and right clicks.-HEIGHT/SLOPE OF LEFT CLICK BUTTON: Very few mouse manufacturers get this right. At least for my hand. I don't like when this button aggressively slopes towards the desk. I prefer this button to be more domed so my finger tendons aren't stretched to press the button. Another issue that plagues me from a back pain aspect.-INSTRUCTIONS: Some poor instructions. Not terrible, but a legend for the dpi colour scheme (since instructions are black and white and dpi are coloured lights), would be useful. Not a big issue for me since Im not a gamer. Also, they show that the dongle should always be connected to the cord and adapter. Is this correct? I plugged the dongle directly into my keyboard usb port and it seems to work fine.-USB to MINI USB CHARGING: not a huge con, but going forward this should likely be changed to USB to usb-C. Again, not a big issue since most mice people own would be mini usb.WEIGHT: Is very light. could use some weight to avoid inadvertent movements. A palm rest that allows some vertical force on the mouse may suffice in place of weight.LACK OF BLUETOOTH AND DEVICE SWITCHING: At this price point, I see these as something that should be considered. Even for $5 to $10 more it would be a good option. Not a big killer since the dongle works fine, but Bluetooth allows some more elegant options. Especially for laptop users and travellers. Also a good backup if the dongle is lost.NO DONGLE RECESS IN MOUSE: For safekeeping, this should be standard on all mice.I appreciate that this is a thoughtful construction for a mouse. And from what I can see, the company who designs this mouse are in the US or Canada. But still made in China. Hopefully the company exerts good quality controls on materials and assembly.All-in-all, I realise most of this review is negative. With more use, I may come back and revise my rating and/or add more positive comments. I hope the designers take these comments as intended, which is feedback to help them improve the design. Because very few people are doing customizable ergonomic mouses.EDIT: After about 1 week of use.Seriously considering returning the mouse. I downgraded from 3 to 2 stars for the following reasons.1-800 tech support number is USA only, not North AmericaOkay for me since I have free USA calling, but when I called their regular non-800 number during their stated business hours, no answer from either tech support or operator. Operator's mailbox simply states a name and beeps without any indication it is the main company general voicemailDRIVERS: So far the drivers have been terrible.Windows 7: they supply drivers, but windows refuses to use them since they are unsigned. So they get installed, over ride the working default windows drivers, and then the mouse just doesn't work. Had to do a restore point on my windows 7. Thankfully windows created one immediately before driver installation.Windows 10: Drivers and software installed properly. However, seemed to be working fine for a few days. Maybe a recent windows update changed something. But now the scroll intermittently cuts out now. The two solutions to this issue are:-reset the mouse configuration to default via the contour driver management software, or;-unplug and replug the wireless dongle/adaptor.Okay if it was once per month, but not for 3 or more times a day.A note about my photos: the paper strips are lined up exactly with the body of the mouse at it's most extreme length or width (not including the thumb rest). The mouse is at it's flattest prone position as it came out of the box (so not rotated into it's vertical position at all). The perspectives in the photos are a bit deceptive since it looks like the mouse edges go past the paper strips. They do not. The place the paper meets the ruler/tape measure is the true edge of the mouse.