One of the nicest speaker switch/selector that has been ever made. They are well made, all mechanical, and has banana plugs. No fuses or speaker protection. You can also use it in reverse (2 amplifiers and 1 speakers), just be careful!
I would try to do a workup on them but, honestly, there is so much information on the internet, the product speaks for itself. Works extremely well when you power amplifier has only 1 set of speaker taps.
"Extremely low internal resistance for minimum power loss; well below the contact resistance of the amplifier output connectors.
The highest grade of heavy-duty, gold-plated, solid-brass, 5-way binding posts, found only in the finest quality instrumentation-grade equipment.
Glass fiber epoxy (NEMA FR-4 grade) circuit board construction with the widest signal traces for minimum power loss; resistance of less than 0.001 ohms; will not degrade the damping-factor of any amplifier.
Oxygen Free Copper (OFC), internal wire jumpers of 12AWG stranded cable to insure signal integrity."