Hi Jessie.
I believe the mailbox red is called 'Raspberry'. In regards to size, best thing to do is to measure according to the measuring chart on the product page. If your horse usually take a size cob, I would think you would need size cob in OS as well. I can send your measurements to OS and they can confirm the size. It is also possible to mix and match the sizes of the bridle, ie full size with a cob sized noseband if necessary. Feel free to email me if you have any further questions or need help with specifications: [email protected]
Thank you, Katja