Small, plastic support ball, 1" diameter (25.4 mm). It can be used as a support element in a two-wheeled mobile robot. Pololu 952

Support ball with a diameter of 1/2" (12.7 mm) designed for mobile robots Pololu 3pi and Pololu 3pi+ 32U4. Pololu 957

A supporting ball from the Tamiya educational series placed on metal rollers in a plastic housing. Pololu 66

Pololu Universal Aluminum Mounting Hub for 3mm Shaft Pair, 2-56 Holes

A set of two Pololu wheels measuring 32x7mm in white. Fits D-shaped shaft with a diameter of 3mm. Pololu 1088

A set of two 60x8mm black Pololu wheels. Fits D-shaped shaft with a diameter of 3mm. Pololu 1420

A set of two 90x10mm white Pololu wheels. Fits D-shaped shaft with a diameter of 3mm. Pololu 1439

Adapter that allows you to easily mount the wheels on a motor with a shaft diameter of 3 mm using screws size 4-40. The hub fits both round and D-shaped shafts. Pololu 1078

Motor with 25 mm diameter and 52 mm length, 34:1 metal gear, 6 V operating voltage, 0,55 A to 6,5 A power consumption, 280 RPM speed and 6,5 maximum torque. Pololu 1573

100:1 Micro Metal Gearmotor

5:1 Micro Metal Gearmotor HP

A small, low-power motor with a 5:1 metal gear, 6 V operating voltage, 0.02 A to 0.36 A power consumption, 2500 RPM speed and a maximum torque of 0.05 kg * cm. Pololu 1100