The identification numbers on our stems, such as 3S-10H/C, 9H-8H/C, or 12F-5D, all help to determine if this stem is the correct size for you. At your local Danco retailer, you’ll find a book full of stems and near it a gauge. The first number in the ID code refers to the size of the stem as measured on the gauge. The first letter refers to the shape, count, and size of the splines on the stem (the part the handle fits onto). The second number is a sequence number, and the second letter or set of letters indicates whether the stem is for Hot (H), Cold (C), Both (H/C), or a shower diverter (D). Once you have the first number and letter from the gauge, you can turn to the corresponding section of the stem book, which is organized by size, to help find a match for your stem. If you want to save time at the store, you can also use our handy online Stem Finder Tool https://www.danco.com/stem-finder/.