Deltana SDLS480 Storm Door Latch, Rectangular, Tubular Lock

Two numbers decide it. The SDLS480 is built for door thicknesses of 7/8 inch to 1-3/8 inch, which covers most screen and storm door stiles, and it uses a 1-3/4 inch backset, so the bore has to sit 1-3/4 inches in from the door edge. Measure the stile thickness and the distance from the door edge to the center of your existing hole before ordering. The face measures 4 inches, so the stile needs to carry that much surface for the plate to land flat.

Tubular is the latch body style: the mechanism goes through a bore drilled in the door face, and the latch runs out through a smaller hole in the door edge to meet the strike. That is the same prep pattern as a common residential bored lock, just scaled down for a thin door. On the SDLS480 the bore has to be centered 1-3/4 inches back from the edge, in a stile between 7/8 inch and 1-3/8 inch thick. If your door is prepped for a surface mounted latch with no through bore, this is not a swap without drilling.

It is the coating, not the metal. Both are solid brass. Polished Brass carries a clear protective coat that holds the bright yellow look, while Unlacquered Brass is bare, so it darkens and patinas with handling and weather until it goes brown. Buyers who want that aged look pick unlacquered on purpose. If you are matching a fleet of storm doors and want them all to stay identical over time, take a coated finish instead, since two unlacquered latches installed a year apart will not look alike.

The SDLS480 is specified for residential duty, so it suits storm and screen doors on houses, townhomes, and apartment units rather than a commercial storefront entrance. For multi-family work it does standardize well, since every door in the fleet takes the same 1-3/4 inch backset and the same 7/8 to 1-3/8 inch thickness range, and you can hold one finish across the property. A commercial entrance takes commercial grade hardware, not a storm door latch.