Turkish Mauser rear band with Sling Swivel. These will fit on most models of Turkish Mausers, but are made for the M38 rifles. Will fit on several other countries' styles as well. These are used, and are old, so expect storage wear, grease, and possibly rust on some. After a good cleaning, these should be good to go.
First Style is solid, with no retaining screw hole drilled.
Second Style is the style with holes drilled for stock retaining screw.