In addition, an attenuator of this kind is only a solution for overload in a preamp or recorder's input circuitry. It's no solution at all if the sound pressure overloads the microphones.
On the other hand, attenuators are a great, low-cost way of figuring out where overload is occurring and what to do about it. If your setup gets a lot of distortion on the loudest sounds, then as a test, try using attenuators. If the distortion goes away, the input circuit of your preamp or recorder was being overloaded, and the attenuators should be left in place; you've got the best solution right there. But if substantial distortion remains, even with the attenuators in place, then look at the microphones and their method of powering. (This assumes that your highest recording levels are below 0 dB, of course.)