Universal LED Tail Light
This cool mini LED strip fits on any 36mm stack and they are configurable in Cleanflight. Some people refer to it as a 30.5mm stack as that is center hole dimensions. It's a simple but clever design that uses 2 x rubber orings to mount the LEDs. Many x frames use a minimalist top plate and 4 standoffs on the FC stack. These LEDs are a perfect match.