The Loose Ring allows for immediate release and relief from tongue and bar pressure. The bit is immediately reset to a neutral position in the horse's mouth.
The Happy Tongue is a solid mouth piece. It is curved and ported to give tongue relief. The Happy Tongue would be a good place to start if your horse is:
The rider will know immediately if this is the correct bit, as a horse with a sensitive tongue will finally begin to work into, and accept the contact.