On the digital pins side, it contains 18 terminals: 16 normal terminals and 2 extra GND. As to the Analog pins side, there are 16 terminals (12 normal terminals, 4 extra terminals for Vin, 2*GND and 5V) and 2 breakout through holes for 2 additional ADC pins.
If you are searching an ultrasonic ranging module, the HC-SR04 is good choice: Its stable performance and high ranging accuracy make it a popular module in electronic market. It's cheaper than an IR range finder with similar range accurancy and distance.
If you are building a robot with wheels, you need a dual H-Bridge driver like this one.
Double H driver module uses ST L298N dual full-bridge driver, an integrated monolithic circuit in a 15- lead Multiwatt and PowerSO20 packages. It is a high voltage, high current dual full-bridge driver designed to accept standard TTL logic levels and drive inductive...