The Myler Level 3 MBT Shank Sweet Iron Ported Barrel Bit features a stainless steel 5 1/2" MBT Shank with a sweet iron ported barrel mouth (MB 33, Level 3) with 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.