Toklat Myler Kimberwick with Stainless Steel Low Port Comfort Snaffle MB 04Myler Stainless Steel Kimberwick, MB 04 Low Port Comfort Snaffle, Level 2 The MB 04 is similar to the MB 02 in that it will rotate on the tongue and apply tongue pressure, however, it has a small (") port that introduces some tongue relief to the horse. The port allows the horse to swallow and move his tongue when he is moving forward and relaxed, which acts as a release or reward. The mouthpiece is curved, and it wraps around the bars and lips