Chesterton's 23K seals are rod mounted U-Cups, for PNEUMATIC applications. The unique design delivers excellent sealing characteristics. Radiused lip produces a continuous lubricating film which minimizes operating temperature and wear. Ideal for extreme cycle applications. Available in standard sizes. Ideal upgrade for OEM, MRO and aftermarket type seals. Custom engineered sizing, eliminates unnecessary re-machining Custom sizes available without tooling or engineering charges.