I have a matching pair of B&K ST-140 mono amps. Each amp is a mosfet design with output rated at 150 watts each. Puchased used in 1993 from and Austin audio store. I have used them as dedicated amps for a pair of subwoofers and more recently as amps for a church sound system. Due to system upgrades, they have been retired. They are in fair condition with some scratches (see pics) but work fine. I have one original box and one generic box. Buyer pays shipping. PayPal preferred.