Lovely used bit from the incredible bit maker Neue Schule (NS) is one of their most popular bits, and it is easy to see why. This bit's center is flat on the top, prevents full breaking of the mouth piece, with some tongue relief. Designed to accommodate larger or sensitive tongues. New with tags, in size large (138mm-148mm) which translates to 5.5"-5.75". 16mm mouth. Marked FlexZ and Salox Gold. Per NS:

Neue Schule Turtle Top with Flex Eggbutt Bit has a 16 mm Salox Gold mouthpiece and stainless steel cheeks. The increased stability provided by this design promotes confidence and encourages a steady, consistent contact. This bit usually benefits the horse with a short, tense neck. It helps with straightness and enhances the aids for flexion and bend. Salox Gold mouthpiece metal is a high copper alloy specifically formulated to reach rapidly and maintain the temperature of a horse’s mouth, and thereby encourage bit acceptance.