120mm brake disc, typically used for 
electric scooters and some bicycles. 
Material: Made from stainless steel for durability and rust prevention. 
Compatibility: Applicable for Xiaomi M365/PRO/PRO2 models and other models with a 5-hole screw pitch of 25-40mm. 
Function: The hollow design helps in heat dissipation and reduces the accumulation of brake dust. 
Purpose: An essential safety feature that provides a high grip surface for brake pads to slow the scooter.