The Waterford Cable has many smooth flexible components which spread the pressure making it a light mouthpiece. It has a spring-back action of the cable which reduces pressure in all areas. The greater flexibility discourages a horse from leaning on it, it also promotes mouthing and salivation.
The Waterford is usually worn ¼" - ½" or 5mm - 10mm longer than your traditional mouthpiece in order to curve around the tongue and maximise the effect.
Please watch the video below for more information on this interesting and effective bit.
135mm = 5 1/4"
145mm = 5 1/2"