It's a nice simple attenuator that supports from 1 to 41 dB of attenuation with 50 ohm input and output impedance and can handle up to about 5 watts of power and is good to at least 30MHz. It's based on
a circuit in the ARRL Radio Amateur's Handbook.
I plan to use it for a couple of applications. I have an RF signal generator built from a kit that has a fixed output. This will allow me to adjust the output level in 1 dB steps from 100% down to about .02% output level.
The other application, which it was designed primarily for, is to adjust the output level of a QRP transmitter so you can work at lower power levels with the flip of a few switches. The rear panel has a label which lists the percentage of output level and power output for 1W and 5W input) and various switch settings.
In may also come in handy when testing and calibrating ham radio and communications receivers.