This model doesn't upgrade to Amazon's newest operating system which is making side loading 3rd party apps very restricted.  Some people don't like that there are still some of these still available as they have far less strict filters of what can be put on the fire stick. This is a brand new one still factory sealed obtained in a bulk estate purchase.

Here is what ebays AI says:

The Amazon E9L29Y Fire Stick 4K HD Digital is a top-of-the-line media streamer that offers stunning 4K HD digital video playback with Dolby Vision support. Powered by a Quad Core processor, this device delivers crystal-clear surround sound with Dolby Digital formats. With features like Wi-Fi connectivity, voice control, and HDR support, this Amazon Fire TV Stick 4K is a versatile choice for enhancing your TV viewing experience. With an operating system of Fire OS and 8 GB of storage capacity, this black device is a must-have for home entertainment enthusiasts.