What is this (bitting/chifney experts!)

[little_pink_piggies]

I have one of these that I need to sell but I don't know what it's called:

https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-prn1/551545_10151485075977246_506908041_n.jpg

Any ideas? My BHS Stage 4 is failing me..!

 

[TarrSteps]

Tongue grid.

 

[little_pink_piggies]

Thank you!

 

[vallin]

What does it do/what is it for?

 

[amage]

Stops horses putting their tongue over the bit