These are a set of propellers for a H-Class submarine from early WW1. Also known as the Holland 602 design, these submarines served in navies world wide, including the US Navy, Royal Navy, Royal Canadian Navy, Italian Navy, Russian and Soviet Navies and Chillean Navy.
The parts are based on official Electric Boat drawings for the H-Class submarines designed for the Russian Navy, built in Canada and eventually sold to the US Navy as submarines H4-H9.
While designed for 1/72 scale, these parts are similar to those used on other Electric Boat designs of the same era, and could be used in various other models should it be appropriate (depending on scale).
The propellers are 19 mm in diameter and come as a pair with one right-handed prop and one left-handed prop. The propellers are designed to mount to a 1 mm shaft and can be attached using superglue (and possibly soldered if ordered in brass). These propellers will work for any scale model requiring a 19 mm diameter propeller.
These propellers are not tapped for screwing onto a propshaft and aren't appropriate for use for R/C models.