Standard Nathe - 6.5cm ring Ideal for sensitve mouthed horses. £46.95 imperial size: [Choose]5.5"5" Quantity: at £46.95 each Add To Basket A very soft, bendy mouthpiece. Ideal for horses that won't take the contact or for sensitived mouthed horses. The small ring diameter is two and a half inches. New sizes for the standard Nathe are 13cm and 14cm. In other words just over 5" and 51/2". The Pony Nathe comes in one size - 41/2" and the mouthpiece is even slimmer.