Yes they are 025 sheet aluminum, wood fins would break in use. These decoys are designed for spearfishing under the ice and decoy collectors .Decoys are made so that they swim in a circle to attract game fish like Northern pike or musky to within spearing range .There is also a large collecting community of decoy hunting and fishing collecting.
I sell my work on that auction website under ID Mitchelldecoys.
Mitch