In the case of a 100 Watt amp, the output will be about 40 watts. These units will reduce the load on your power transformer and allow your amp to reach distortion with a nice AC-30, or EL-84 sound and feel at levels that are lower, and more friendly to recording studios, and venues where your amp will not feel, play, or distort at the amplifiers normal higher sound levels.
If your a studio musician with a painstaking need of practicing at reduced power, or specialized studio work, then this product is your ticket to success. Rest assured you are dealing with a professional. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Parts & Accessories\Vintage Tubes & Tube Sockets".The seller is "ectcoinopllc" and is located in this country: US. This item can be shipped worldwide.