Stands for the Xiaomi Mijia thermometers. One is vertical and the other is angled 20° back.
The fit is snug enough that it could also be used on the side of the thermometer for side mounting on a wall or something.
The model shown is the LYWSD03MMC. I'm unsure if other models will fit.
The inner dimensions are 13mm x 45.5 mm x 8mm
The author marked this model as their own original creation.