I found this interesting article on the use of Switch rods, here

Links to other resources

Understanding Switch Lines

​Spey Line Spec Chart

Spey Line Recommendations

Understanding Spey Lines

Files

Welding a loop in sink tips

Choosing a Spey Shooting line

Choosing a Spey line

Videos

The Spey world is pretty complicated, with a vast array of tackle (especially fly lines) to confuse the masses. This page is designed to provide a few resources  to try and make some of it a little clearer.