The (MBOT-SKIT, discontinued) comes with the mBot and 2 add-on packs: the Variety Gizmos Add-on Pack, and the Perception Gizmos Add-on Pack. The electronic parts list is as follows:

mBot:
Ultrasonic sensor
Me line-follower sensor
IR receiver
Light sensor
Buzzer
IR transmitter
Right and left drive motors
2 – RGB LED
Button

Variety Gizmos:
RJ25 Adapter Module
RGB LED Module
Seven-segment serial display
Servo pack
2 – Micro Switch (touch sensor)

Perception Gizmos:
Temperature and humidity sensor
Potentiometer
Sound sensor
Motor pack (fan)
LED Matrix (8 x 16)

(MBOT-SKIT, discontinued)
mBot Troubleshooting and FAQs