Tip diameter needed for the Titleist T200 iron is .355″. As far as a ferrule goes, the outside diameter of the top of the hosel on the 2020 version that I measured is approximately .525″, so you would need a ferrule with at least that diameter. Most of our aftermarket ferrules for tapered irons are .535″, which will work and can be turned down flush for a clean look. We have several to choose from, depending on if you want a ring on them or just black, and depending on the length you want. We have some specific Titleist collard aftermarket ferrules for the AP1 and AP2 irons, but they could work for the T200 if you needed the collard ferrule. Best thing to do is go tour website and look at all the options. Our stock black tapered iron ferrules are listed at the link below.