I ordered an Withings Sleep and and VEYKOLOR PRO at the same time. A difference between day and night. The packaging of the VEYKOLOR PRO was OEM style. Well, we throw away the packaging, but it is the first indication of attention to detail. The included Operating Instruction manual basically discussed the elements of the device, the buttons, and how to pair to the app. There is no description of information on the screen and the meaning of the screen. MOST IMPORTANTLY, the manual and box are missing manufacturer information, no e-mail, no website, no address, no name. The app is the same. No manual, no contact information. I would avoid any product of an "anonymous" manufacturer.

The Power OFF feature is troublesome and poorly documented. 1) the calibration cap must be removed. 2) the button must be pressed for upwards of 10 seconds. 3) the unit must be pointed towards something that will not register as a color; such as down a hall.The product app has a large open source following that should provide for continued improvement and software upgrades. Such should also allow for universal ISO improvement of color development such as mixed color and sparkel registers.

I am writing this in a sleep deprived state so forgive me if this is rambly..The app was a bit of a pain to get working, at least on android. My first attempt at a review included a link to the place where you can go online and register if registration isn't workign on the app, but my review was rejected for including an external URL. So, browse through the customer questions and you can find it if you have trouble.But on to the review... The accuracy is pretty nice. I tested it against the LAB values for an individually measured color chart (after setting the illuminant and degree of view for the colorimeter to match the illuminant for reference values for the chart) and the values are pretty close. Results are also pretty consistent when measuring the same item multiple time. So, this is pretty accurate so far!The app has many color systems and metrics you can use, and you can set the illuminant and degree of view as well. However, note that if you measure a color with D65, the change to D50, it is simply telling you the location of that color as mesured with the device's LED in the color space assuming either of the white points. It is not using a chromatic adaptation trasformation or altering the white point of the LED to measure how a color would appear under a specific illuminant. Unfortunately, when I asked the company about the color temperature and spectral density function of the LEDs within the device they did not know, but I assume that since the default setting is D65 that the LED is somewhere within the vicinity of a 6504K white point. But how well it approximates D65, who knows.This relates to another flaw with the device & app. It offers a metamerism measurement. Metamerism refers to objects with different spectral density functions which appear to be the same color under a particular illuminant. The purpose of a metamerism measurement is to test for metameric failure. For example, let's say I have two cards painted with different brands of paint and when I look at them outside in the daylight they appear identical. That's a metameric match under daylight. If I take them inside and I have fluorescent bulbs for lighting, one appears to have taken on a magenta hue. This is metameric failure.Since this device cannot actually change the illuminant used for measurement the metamerism metric is probably meaningless. To measure metamerism you need to measure two different samples under two illuminants. So, sample A would be measured under D50 and fluorescent and sample B measured under D50 and fluorescent for a total of four measurements. However, the metamerism measurement in the app only accomodates two measurements. This only affords the ability to test a single sample's color appearance against itself under different illuminants. However, since the white point of the LEDs in the device can't actually be changed the app always reports PASS no matter what you set the illuminants to in the app.Nevertheless, this device is very useful. I appreciate that it contains so many color spaces to report values in, including CIE LAB, CIE LUV, CIE LCHab, CIE XYZ, RGB, HSL, among others. I do wish it contained CIECAM02 or CIECAM16's Jab and Jch spaces, but one can't have everything I suppose. Do note, the RGB values reported are tone-curve corrected sRGB values. So, they are not linear sRGB, and if a measured color would fall outside of the sRGB gamut the reported RGB values are clipped. But, no clipping is applied to LAB or XYZ here.For 70 dollars this is an incredible value regardless of the flaws I mentioned. I do recommend using a secondary email address when creating your account with the app. Since the app isn't even on google play, who knows how secure the app is with your information.

1) It can be a pain to get working with the app. (Which is odd that they don't put the app on the play store.)2) There is very little documentation to help you with this.3) The 1 button interface is rather confusing, and it doesn't make much sense. Again better documentation would help with this.4) This unit measures its own white point as (RGB #DEEEDE) which is an off white color. (I tried recalibration many tines.so either this is the intended result, the device I got is defective, or the software/device can't calibrate itself correctly.) Again better documentation would help figure out which is true. [Edit] I figured this out, the reference white point, is not a pure white. And is not the whitest color the device can read. Had to compare it in daylight to figure this out.5) The unit can't measure glossy surfaces very well, e.g. it measures the back of its own calibration cap as the same color as its whitepoint calibration. (At least I hope that is what is going on. As I don't have very many non-white glossy surfaces to test against.)6) You need the app or other software to change to other color spaces for which you would be more familiar. Not many applications, or other softwares use the LAB color space natively. [Edit] the units native screen can have its color space changed in the app.This device needs to be better documented. Its not bad, just very confusing. Now that I understand it, I. Mu h happier with it. Just wish the app didn't feel so sketchy.Does it really need a login?How do I get reference colors which are things I recognize, and not written in Chinese?Would it really be so bad to add the app to the Google play store?

I scanned several different color blocks and the codes never changed. It just doesn’t work. I also was not able to connect to the app since it never sent me an email. I tried two different emails and checked spam. Never received anything.

I was able to test this device on the laminated floor sample. As the one I’ve used is out of stock but my contractor has to keep working and get my floor done, so I bot this to shop around to find a close color that I am to use for my kitchen floor. I didn’t want to waste my money at the beginning but the contractor told me to get this device from Amazon, so I would also use for my wall paint color as since the covid that I have to complain that many materials are out of stock quickly and we want to move into our new house. It’s really easy to use and I especially like the color and portable design. So far it looks like a perfect addition for my new house decoration. Hope it would last for long time.