This is a ThumbsUp TU-EP-1 thumb rest grip made by matchTechnicalService, a standard accessory specifically for the Leica M9 / M8. Perhaps due to the Kodak CCD boom of the M8 and M9, they've become less common. It's from nearly 20 years ago, and as the photos show, the brass is starting to show through, giving it a cool,渋い (shibui - understated, cool) look. How about improving the handling and dressing up your LEICA M8/M9 when taking photos? This product is made exclusively for the M8 series and M9 series. Please note that it is not compatible with the M10, M11, and TYP240 series. Thank you for your consideration.