When we were trying to get our final inspection, we failed because the wood handrail was wider than 3". To solve the problem we hung a galvanized pipe on the adjacent wall using these slip-fittings (this was before I could really weld). You can buy these fittings online but they're kind of pricey. Luckily, I found mine at Harbor Freight, they were the last ones and I've never seen them carry them again.