Rubber Tongue Loller / Juba Port /Tongue Layer

Rubber tongue lollers, also known as a tongue port or juba port, are used on a reasonably thin mullen or jointed bits to help prevent the horse from putting its tongue over. Best seen as a temporary measure until a more suitable bit is found, the tongue loller is made from flexible rubber and is fitted by looping it back through itself, around the centre of the bit pointing up the mouth.

You can then consider tongue relief bits - giving the tongue room to be more comfortable or different restriction bits.