* (Unfortunately none of these products are available yet, and probably never will be. Some of these designs are over 10 years old. There are newer altimeters on the market from other people that have features mine don't, so my devices wouldn't sell enough units to make it worthwhile manufacturing them. Also, my host software was written in Visual Basic 6 (VB6) for Microsoft Windows only (not macOS or Linux), and Microsoft dropped support for VB6 years ago. I'm reluctant to spend the time it would take to completely rewrite the host software in another language. Instead, I will probably eventually just post the schematics and PCB layouts, and maybe the source code for the microcontroller firmware and VB6 software, in the hope that someone will find them useful, or at least interesting.)