The Data Logger comes as a kit of parts, with a Printed Circuit board: - uses AXE015X 18pin Picaxe which is supplied An IC0011 (DS18B20 One wire Temperature measuring chip) and an LDR for measuring light intensity are supplied There is a 24LC16B EEPROM chip and other components to get a Data Logging system going. A Real Time Clock kit is available - AXE034 (same RTC kit as used in the LCD display AXE033).