(1) 3 mosfets for heater / fan outputs and 3 thermistor circuits.
(2) Pololu boards are on pin header sockets so they can be replaced easily or removed for use in future designs.
(3) All the Mosfets are hooked into PWM pins for versatility.
(4) Servo style connectors are used to connect to the endstops, motors, and leds. These connectors are gold plated, rated for 3A, very compact, and globally available.
(5) Fused at 5A for additional safety and component protection , Heated bed control with additional 11A fuse .