spring tension
 

I' ve never had an prong type arrow rest before and I was
wondering if anyone could tell me what the spring tension
is for? and how much tension should I use? The rest I got
is a Cobra Sonic.

RE: spring tension
 

For the NAP Quicktunes they recommend just enough tension to hold the arrow up. I would imagine it would be the same for you.

RE: spring tension
 

The rule of thumb I' ve always gone by is heavy enough to hold the arrow up, but not so heavy that, when you push the arrow down and let go, that the prongs will come back up hard enough to bounce the arrow off the rest.

If you go too light, the weight of the arrow will cause the prongs to droop down. There is a school of thought that sets the tension light enough for the prongs to droop, but raise up as the arrow is drawn. I' ve always gotten groups that string out vertically when I' ve tried it.