the pelt or fur (especially the underfur) of a seal
<noun.substance> a coat of seal
a garment (as a jacket or coat or robe) made of sealskin
<noun.artifact>
Sealskin \Seal"skin`\, n. The skin of a seal; the pelt of a seal prepared for use, esp. of the fur seal; also, a garment made of this material. [Webster 1913 Suppl.]
"It became shameful to be seen in a sealskin coat," complains Adolf Jensen, a hunter from a small village 250 miles north of the Arctic Circle.