Is there only one size ?

 

No they come in a few sizes.I tried them and they made my exhaust sound like I had a washer in my pipes. Oh Wait! I did. I noticed zero improvement in anything and took them out.

 

Torque cones/power cones are nothing but a band-aid for a shitty exhaust system!

 

I had torque cones in my last exhaust. They were the original generation Samson Rip Saws. They were 1-3/4" drag pipes (no baffles) . My bike ran great with that setup, but the exhaust was outrageously loud, so I switched to a Fat Cat after a few years.
I've read where some people say torque cones don't help, but I was happy with the setup.
Tom