Myler BitsMBT ShankSweet IronForward Tilted Port5.5 Inch Shank89-61365 Stainless Steel 5 1/2" MBT Shank with Sweet Iron Forward Tilt Ported Barrel (MB 36, Level 2-3) Copper Inlay. This mouthpiece is made of polished Sweet Iron which naturally oxidizes or rusts. Harmless to horses, it has a sweet taste and promotes salivation.