Yess I found a bit I am looking for!
Solid Colt Mullen. 5/8" Sweet Iron Mullen Port. Colts that have a lot of natural flex can use this bit to learn curb pressure and help collect themselves without over flexing. This mouthpiece is especially gently for tugging a young horse around.
My horse is ultra sensitive to curb pressure but I have to ride him in a curb for practice in W/p since he is over 6 years old so I'm trying to ultra-slowly introduce it to him again, since he was ridden in curb when he was about three or four but not since then, I want to do it without using an Argentine or tom thumb.