If you have a cheap recurve like I do, then yes they are necessary. They help to an extent, but what I found to be the most help was I switched to a flemish fast flight string and not only did the bow pick up a few fps, it quietened it down a bit too. I made little rubber gaskets out of bicycle innertube and put them between the limb and the limb pockets. I like to take the catwhiskers and tear them down the middle and make 4 smaller silencers instead of 2 big ones. I space them equally apart and it seems to work well. Heavy arras help too. All this helped turn a really loud cheap recurve into one that is now what I consider to be "hunting quiet."