Here is a weekly list of BNC Attenuators

Bracke Manufacturing supplies coaxial attenuators manufactured with either machined brass connectors or passivated stainless steel versions.  The product line includes low to high power attenuators with a power handling range from 1 Watts to 100 Watts, frequency ratings from DC to 50 GHz, and an attenuation range from 0dB to 110 dB.  They are available in 50 Ohm and 75 Ohm impedance variations.  Typically the attenuators are male to female and can be bi-directional and directional, depending on the power rating, and are available in 2.4mm, 2.92mm, 7/16 DIN, BNC, F, N, SMA and TNC connector versions.  Heat sinks on higher power version are extruded aluminum painted black.