Check the listing for details. 12 Golf 3/4" Black Ferrules .370" for Parallel Tip Iron Shaft. Condition: New. Listed at 9.99 USD. Buy from US Seller!Support our Veteran!Your are Buying:Dozen of Iron Ferrulesfor .370" Parallel Tip Iron shaftBlack Length: 0.76" Outside Diameter (base): .550"Inside Diameter: .368"High-Gloss Finish Shipping: USPS 1st Class. The .370 iron ferrule must be tight to prevent loosening of the golf club later. When you come across a tight ferrule during the installation process, try these tips: Use a rat tail file and make a few passes down the ferrule’s inside, and thenSoak the ferrules in hot water for 10-20 seconds while you prepare to build the club, Or, Dip the tip of the shaft in acetone, andUse a cotton ball dipped in acetone to wipe the inside of the ferrule (try not to get it on the outside of the ferrule). Do not take drill bits to bore the ferrule; this will most likely lead to screw-ups. Before starting the process of installing ferrule, please also make sure the chrome of the shaft tip has been ground off and no epoxy remains.