Recoil Spring 92FS Opinions Needed

[Allay]

http://greenvalleygunrecoilsprings.com/cart/index.php?main_page=index&cPath=8

I'm looking for opinions / guidance on the above product.
Seems like a sound idea to me, but what do I know.
I shoot reloads and store bought in a Beretta 92FS.
Thx for your time
Allay