This is equivalent to Shimano's genuine part number: TL-FW40. ① Single 2-prong, prong width 3mm Upper section: ∮26-∮32mm, Lower section: ∮32-40mm Requires a 24mm wrench (or adjustable wrench) to turn. Although unopened due to inventory, there is some surface rust. However, it's at a level that won't affect performance if you apply rust inhibitor or chain oil and wipe it off. Thank you for your understanding. I will not accept price negotiations for this item alone. Thank you for your understanding. I will consider discounts for bulk purchases or combined purchases with other items, so please comment. Please purchase without commenting unless you are in a hurry. (Shipping may be delayed by a week or more due to long holidays or business trips. If you are short on time, please be sure to contact me in advance to confirm the delivery date.)