Infra-Red Relative Distance Indicator  -  Shows how close you are.

   Musical Pitch sensor - Use musical notes to control your robot.

    Acceleration/Tilt sensor - Make a balancing robot.

   Air Pressure sensor - Measure pressure in your air cylinder.

    Switch Multiplexer - Connect 3 switches to one RCX input.

   Passive Infra-Red sensor - Detects movement of people & animals.

   Current sensor - Measure how hard your motor is working.

  Three-wire converter - Easy-to-use sensor interface for Mindstorms.

  Angle sensor - Measures 0 - 270 degree angle accurately.

  IR Flame sensor - find a candle or other InfraRed source.

   Force sensor - Measure how hard you are pushing.

   UV Flame sensor - Withdrawn

  Infra-Red Proximity Detector - Withdrawn

  Dual Infra-Red Proximity Detector - Withdrawn

  InfraRed Relative Distance Indicator (side viewing) - Special Order