Welcome to the forum.
Because of the 4" barrel it has a square butt grip frame as shown above and is a ".32 Regulation Police".
If it's not marked MOD 31 stamped in the yoke when cylinder is swung open to the side, it was produced after 1953 but before 1958 and is specifically known as the "Model of 1953 .32 Regulation Police".
However, the serial # is a couple of thousand above the lowest serial #s I have in my database for the lowest recorded model stamped .32s which was ordered in June of 1957.
So if yours has MOD 31 stamped in the yoke, it's the same gun but from 1958 to 60 production and specifically known as a "Model 31, ".32 Regulation Police".
It says "No safety" on the box label? Printed or handwritten?
Yours must look like this, but with thinner grips and w/o the target sights:
