what is better and where can I get one?

Niether. Save your money for ammo.

Quoted: Niether. Save your money for ammo.

Ditto!
Lone Wolf carries the sprinco, but for the 9mm I think it would be a bigger headache then a benefit. If you are just worried about the guide rod breaking I would get one in SS and a #18-19 recoil spring. Any higher weight spring and it might not function.  

can you guys elaborate why? don't they work as advertised?

I had a Hartts unit in my G21 for a while.  It produced a noticable effect with the hotest loads...but only slightly.    With practace quality loads you couldent tell if it was in or out of the gun. Newton says there's no free lunch....the most that can be done is to change the timing of the recoil and that's really not worth that much. Quite honestly I think the added weight was worth as much as the mercury and balls.  And that's with a 45.....with 9mmm?   pffft.  

If you've got recoil control/tolerance issues with a 9mm you need training not an aftermarket accessory.  

I don't mind the recoil as it is very minimal as it is as I'm coming from a 1911. I was just wondering if these aftermarket accessories will further improve them or is worth the $. I guess I just saved some $$. Thanks.