I'm pretty sure it's an Advance 71A1800, which is HX autotransformer, but I need to find it.

Btw, both 50w Advance mercury CWA and HX ballasts can be seen here next to each other.

For example, here is an example of a Japanese 400W mercury vapor ballast that is still being made:

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=H4TC1A51

In Japan, I still see the mercury vapor ballasts still being produced, but only the lamps have been banned.

@ HID Lad, more than likely, and with all new installations of MV banned, it's the only logical thing for them to do. 

@ WWHID, they banned them because they could... 

I am also wondering why the selection of self starting mercury vapor retrofit lamps in other countries was more limited like in the USA or the EU countries and why the EU decided to ban high pressure sodium retrofit lamps.

Probably because the vast majority of their HID street lighting is mercury vapor, and municipalities want other more energy efficient options that will work on the existing gear without needing to change anything.

While looking at Japan’s HID lighting portfolio, I have noticed that they definitely have an amazingly large selection of mercury vapor retrofit lamps that encompass nearly every HID lighting technology ranging from high pressure sodium, white high CRI high pressure sodium, quartz metal halide, and even ceramic metal halide! Additionally, multiple manufacturers such as National/Panasonic, NEC, Mitsubishi, Iwasaki, and Toshiba made these lamps!! The amazingly large selection of mercury vapor retrofit lamps that Japan offers makes it tempting for me to import them for my own collection. Why was there a need for Japan to design a self-starting mercury vapor retrofit lamp for nearly every HID lamp technology and why did most other countries largely develop dedicated ballasts different from mercury vapor ballasts and external ignitors for the other HID lamp technologies instead of self-starting mercury vapor retrofit lamps like Japan did?

Here is a video that clearly shows the wide variety of mercury vapor retrofit lamps available in Japan if you want to see what the lamps look like warming up:

https://youtu.be/rAfEUeZFNUI?si=sjJJysqTAwcFarUC

In the video, you can see a mercury vapor lamp, a high pressure sodium retrofit lamp, a quartz metal halide retrofit lamp, and a ceramic metal halide retrofit lamp all being used on the same mercury vapor ballast.

Nowadays, LED lighting is known to retrofit nearly every existing light fixture out there in most countries.

Just curious. Are your 50W ballasts CWA ballasts or HX autotransformer ballasts?

Well, it got declined. If this seller ever wants to sell this ballast, they have to lower the price to something more reasonable.

I think I may have two. What would you like to pay for a genuine 50w MV ballast?