Anyone have either to trade?If so e-mail and I'll let you know what I have to trade.Debbie

I haven't found snow a problem with either type of cap on my house in S. NH, although differences in detail between mine and these, as well as in roof slopes, may make one or the other better in your application. For flow, attempt to determine for your duct size what the dimensions of the respective choices are. Then you can calculate the flow area. Correction for bird screening may have to be approximate. Alternatively, and better if you succeed, ask the manufacturer for the pressure drop vs. flow characteristics. kas

Sometimes an attempt to keep water out only serves to trap it in. Water may eventually get under the material, through nail holes for example and then sit, unable to evaporate. There was an article in Fine Homebuilding last month, volume 196, "Smater Deck Framing" and it didn't mention capping joists, though the builders did use an "isolation membrane", self sealing flashing tape from Grace called Deck Protector, to isolate any joist hangers from wood. This is because they're afraid any treatment product, (ACQ), will speed corrosion of the metal in the joist hangers. The material was just wrapped around the ends of the joists where they sit in the hangers. Seems to me if you use anything to cap a joist it should be something like this "Self-sealing" product. Just a guess.

Hmmm. I still have a few that you sent me, so I'll have to give them a whirl. I don't know why, but I've never used the Caps on clothing -- I've always reserved them for kitchen linens and extra dirty towels. I think it's the scent. But now I'm curious and will have to give it a try.