I was testing the HD19a and it seems to have an issue with battery drain.
Twice I have pulled it out to use it and it won't power up despite having recently replaced the batteries.
I am just going to say it, I don't trust their products, I tried 2 versions of the digital NV scopes and both of them were not reliable.
I was constantly trying to adjust the HD19A as well.
I spent the weekend with an Eotech X320 and it's just so much simpler to use and worked great.
While I agree the Eotech is much simpler in operation and is more compact and rugged I was very disappointed in the picture quality. The tiny screen was a big disadvantage over the pulsar line. Not to mention the Eotech only gave a year warranty while pulsar gave 3. The image quality of the eotech was also much poorer than the pulsar line. The 384 sensor is a noticeably better image. I have owned both the Eotech x320 as well as the ATN OTS-X and felt like the pulsar outperformed both of them. With the pulsar (or any thermal or NV for that matter) its best not to store them with the batteries in. I believe the pulsar has a clock function and that's what drains the batteries. I do like how the pulsar uses a battery pack and includes a spare. Much easier than removing one battery at a time. The custom color feature of the Eotech is pretty cool but I found the standard white hot/black hot was what I went to mostly. I like the OTS-x but it was pretty bulky and I didn't care for the menu operation. Didn't seem well thought out. One other huge plus for the pulsar that the others don't offer is independent contrast and brightness adjustment. That makes a huge difference in less than perfect condition. Of course all that is just my opinion but I have owned all three of those units and the only one I've still got is a pulsar.