I just finished replacing all of the baseboard radiator enclosures in my house (12 in all). You have already finished the hard part of removing the old ones. I bought Slant-Fin brand replacement enclosures from my local Home Depot. They are available in 3, 4, 5, 6, & 8 foot lengths, and include 'splice kits' if your radiator is long enough to require more than one enclosure. Also available are end caps with access flaps (left & right - be sure to get the right ones), as well as inside corner pieces. My Home Depot had them only in Slant-Fin's NuWhite color, which is a little off-white. I just finished painting, and stayed neutral, so the color was acceptable (anything looks better than the old ones!). I am not sure if they are available in other colors. A tip for shopping: right next to the enclosures, the Home Depot also sells entire radiator units (including pipe and fins) in a box about the same size as the box that the enclosures come in. Be sure to get the enclosures only - it is lableled on the box, but not in huge print (I made it all the way to the register before my wide pointed out that I had the entire radiator!). You will obviously notice a big price difference! My old enclosures were nailed to the studs prior to the pipes being run, and I had a tough time pulling the nails. In case I need to ever remove them in the future, I installed them using drywall screws (they will go right through the back of the enclosure if you push a little). I screwed them into every other stud, but always drove a screw as close to the end of the enclosure as possible. Before you install the enclosures, it is a good time to install new bleeder valves if you need them. They will allow you to get the air (and therefore knocking) out of the pipes. I had a local plumber do that for me, I believe he charged me $25/valve. Be sure to line up the access flap on the endcap with the bleeder valve, so you don't have to remove the entire front of the enclosure to bleed the pipes.