The Range Finder can measure up to a 15 foot distance.  When the unit is scanning it will show red leds then back with blue.  The 5 led bargraph is split into 3 different measurements.  When blue is lit, its odd numbers, and purple is even numbers.  Once it measures 11 thru 15, the tail end will have the purple leds will turn blue and shutting off the red led on the dual leds.