From the Manufacturer
TCS - The tubeless compatible TCS rim profile is especially designed for TCS or UST tires and is also compatible with tube type tires when used with tubes. 4D - Drilling process creates the optimal interface between spoke and rim. This exact angle reduces binding and the need for eyelets. I-Beam - Pioneered by WTB in 1994. This distinctive, centrally located vertical support counteracts spoke loads and provides torsional rigidity. CID - Any bicycle dealer or qualified mechanic can service each of the components of a TCS wheel set or rim without the need for special tools or shipping delays. 7000 Series - Super light, superior strength. On-Ramp -Provides a consistent fit between rim and tire for easy installation and inflation.