Display your Tamarancho Annual Ride Pass, visibly and securely, from your seat post. TagBone fits all seat posts from 27 mm to 31.6 mm. If you have more than one bike, it's a must have. The TagBone could also be used to display any standard luggage tag with team logo, race number etc.., just clip it on and go. TagBone weighs 6 grams.