Deltana SDL980 Storm Door Latch, Round, Tubular Lock

Tubular. It goes into a bored hole through the door face at a 1-3/4 inch backset plus an edge bore, rather than a rectangular mortise pocket routed into the door edge. If the door you're replacing on has a mortise pocket cut in the stile, this won't drop in without new prep, and you want a mortise-style storm door lock instead.

No. The SDL980 is a residential storm and screen door latch, built for the secondary door in front of an entry door. It tops out at 1-3/8 inch door thickness and carries no security grade, so it isn't the part for a building entrance or any opening in a means of egress. For a commercial entry you want a Grade 1 or Grade 2 cylindrical or mortise lockset.

Solid brass throughout, not a zinc casting with a brass flash. That matters on a storm door because the hardware sits in the weather on the exterior side, and a solid brass body won't pit and swell the way plated diecast does. It's why the unlacquered brass version can be left to weather on purpose.

It depends on the old prep. The SDL980 needs a 1-3/4 inch backset bore, and a lot of factory storm door handle sets use a different backset or a mortise pocket. Measure from the door edge to the center of your existing hole first, and check the door thickness is between 7/8 and 1-3/8 inches. If the backset matches, the round escutcheon gives you some coverage of minor wear around the bore.