Hydraulic disc brake. E-bike ready: Yes. Mounting caliper: Postmount. Brake fluid: Mineral oil. Number of pistons: 4. The Shimano BR-MT520 caliper is a powerful 4-piston caliper with a minimalist design. It is designed for use with mineral oil, which is non-corrosive and less hazardous than conventional hydraulic fluid. The caliper can be mounted without a bracket, allowing for quick installation and setup. Additionally, it is compatible with international standard and postmount forks and is intended for use with Shimano hydraulic brake levers. With the Shimano BR-MT520 caliper, you benefit from efficient braking with minimal effort.