Thanks very much Tom ....... will try and do a bit more research.
Keith ..... can you explain a bit more on which type (floating, sinking or fast sinking) to use and what kind of lure (fly, SP or HP) to use with it please?
I imagine their body weight depends on how far you need to cast it .... or .... will the sinking ones, for example, all sink at the same speed regardless of the body weight?
What situations would you use them in to gain an advantage?