This Heathkit SB-220 / SB-221 Replacement Capacitor Module Kit, is an upgraded replacement filter capacitor block for the Heathkit SB-220 and SB-221 Amplifiers.Most Heathkit SB-220 and SB-221 Amplifiers are 20 to 30 years old and the older capacitors are all starting to fail and many are leaky.It is only a matter of time before one or more will fail and go up in smoke or short out and take out the transformed windings.Transformers are very hard to find and are very expensive if you have one made.There is no reason to wait for a failure, when you can install this easy to build kit! This product features high-quality USA Made, computer-grade Cornell-Dubilier 210uF, 450VDC electrolytic capacitors. The bleeder resistors dissipate about 30 watts less heat than the original Heathkit design so it operates a little cooler. The kit assembles into an easily-installed block. Two mounting grids are included.