The Heathkit SB-220 SB-221 HF Linear Amplifier Fan Motor & Blade is a brand-new replacement part specifically designed for the Heathkit SB-220 model. This quality product ensures smooth operation and efficient cooling for the SB220/221 radio amplifier. These have been successfully installed in 18 amps now. Buy with confidence. One seller got one blade broking in shipping, and I sent him another one free of charge to replace it. I stand behind what I sell.