The T Series was designed to be used as a cap or a plug and are tapered to fit a wide range of applications to protect from contaminants and debris. These caps/plugs may be used for mil Std, sae-type fittings, hydraulic and threaded or non threaded fittings. The tapered design allows the opportunity to cover a vast range of cap or plug applications. Easy to install or remove.:: a: 0.299, b: 0.365, C: 0.235, D: 0.302, E: 0.38, F: 0.5.