This is a stainless steel flat shank bit made by renowned bit maker Ron Myler USA, with a medium high port mouthpiece #13.  Unlike the Myler Toklat bits that are commonly found , this is a genuine Myler USA bit which means it is not only Made in the USA, but is higher quality construction than the imported Toklat licensed bits.  This is a well maintained pre owned bit with minor surface wear on the shanks and very light rusting on the sweet iron mouthpiece.  The loose shanks measure 7-1/2 inches long with a 2-1/4 inch purchase for a 3.33 to 1 leverage ratio.  The mouthpiece is Myler's #13 solid 2 inch tall by 2 inch wide curb mouthpiece and measures 5 inches wide by 3/8 diameter.

The 2 inch tall port sweet iron mouthpiece is shaped with a curved forward tip to perfectly fit your horse's mouth and provide tongue relief.  This mouthpiece offers a variety of pressure points to take the horse as soft as possible. The mouthpiece is made of polished Sweet Iron which naturally oxidizes.  The port on this mouthpiece applies palate pressure and is a level 3 bit for a finished well trained horse that performs on a full drape and is the most severe Myler mouthpiece in terms of pressure.  The horse that goes well in this mouthpiece has a trustworthy and consistent disposition, trained to work off the leg and seat as well as the hands.  This mouthpiece has fixed shanks and features copper inlays to promote salivation and a responsive mouth. 
 
The MB 13 does not rotate on to the tongue, but instead sits solidly across the bars and lips of the horse’s mouth. The port is narrower than most Level 3 mouthpieces, but still offers ample room for the horse’s tongue to pass under the bit easily.  Because the port is narrow, when the reins are engaged, the horse might feel a slight pressure on the outside edges of the tongue — a gentle reminder rather than a strong reprimand.

 This bit is considered by Myler to be the most demanding of the Level 3 bits for the following type of horse: