This is a seatbelt alarm stopper for Suzuki Ignis. May work on other cars too.
If you want to measure: The "tongue" without the handle at the end is 21 mm wide, 37 mm long and 3 mm thick. The thin parts around the hole are 5 mm on the left and right side and 6 mm on the front.
Use at your own risk! This thing may not be allowed in your country!
The author marked this model as their own original creation.