If you are installing a Delta faucet in your bathroom, make sure you have all the parts you need. I made the mistake of replacing the faucet that came with the house, which had rubber hoses running all the way to the wall outlets, and I didn't realize the Delta replacement didn't come with hoses — only the short copper ones.
On top of that, I should have checked more carefully because Delta uses 1/2-inch connectors, and I screwed up when I went to Lowe's and bought a 3/8-to-3/8 hose. I had to make another run to the hardware store to swap it for a 1/2-inch-to-3/8-inch hose.
AI said there was supposed to be an adapter from Delta, and technically there is — but Delta only sells the official RP63263 adapters as a 4-pack kit, not individually. That's why the price is around $40. If you only need one, generic 3/8-to-1/2 adapters or hoses are way cheaper.
And always make sure to cram that angled-edge gasket up into the sink before tightening the big connector that screws up into the sink.
Also, don't assume the hot-water connector coming out of the wall is on the left. At least that last one was an easier fix than having to undo all the drain pipes and reconnect them.
This whole faucet replacement job reminded me of back in the day when I went to ITT Tech for mechanical engineering. There was an older gentleman in one of my classes who was there for architecture, and he told us a story about doing construction work before coming to the school. He was installing a sink and didn't think it needed the P-trap under it, so he ran the drain pipe straight into the wall. He couldn't understand why the U-shaped trap was necessary.. That little big of water in the bend is the only thing stopping your bathroom from smelling like a municipal waste facility.