Hi kosst
Thanks for the question. The BEStrip-Type 3 is usually the one chosen for preamps. That's an effective gauge of 17. The BEStrip-Type 4 usually amps is effective gauge 16. If you want to step up to the 20 gauge the Type 3 is effective 15 and Type 4 effective 14 gauge. You work your way up from there.
The BEStrip-Type1 at 20 gauge is for light pulls like small effects units and simple sources like the Maggie player I use.
The rails inside are typical thin copper plates.
The BEStrip-Type 1 was tested on full size amps with no fatigue on the line (sounded great) but I don't recommend amps with this. Right around Type 3 is pretty nice. I also do a Type-5 at 15 effective gauge which sound pretty nice. Monster amps should really go direct to wall (no strip if possible). And I try to have them around 14 and into the wall at 14 gauge Romex, nice sound. Many codes stay at 12 gauge Romex though.
It really comes down to how your doing the house, outlets and what components. The component internal wiring is, as you know, a big deal. So I try to make a plan to keep all things balanced. Metal conduits can really screw with the formulas so you have to stay informed. Some homes for example have conduits as code and others Romex straight is fine. But there is a formula for every system and one can sound great with one set of components and then another set goes in and it's terrible, but it has nothing to do with the components as such, it's a mismatch.
Anyway I hope this clarifies a little.
Michael Green

