In legends from central Europe, especially in countries like Germany and Poland, it was believed that someone could become a werewolf by wearing a special girdle or belt. This was called a Wolf Strap. It was a magical garment, but also cursed. Whoever owned it wouldn't be able to get rid of it, no matter how. Those who accepted a magical wolf strap would be connected in body and soul to the dark forces, including the Devil.
A witch could turn a bride and groom into wolves at the wedding feast by leaving a wolf strap, human flesh and wolf pelts. Dressed in furs would encourage them to transform willingly. Wolf straps were potent more so if made from wolves or hanged men! But the wearer would be more successful changing into a wolf properly if they were a witch and were the ones who made the strap!
Here is a quote from A. Wuttke Der Deutsche Volks und Aberglaube der Gegenwart (1920):
“People (men, women, even boys) change, mostly just for several hours, into wolves by wearing a wolfbelt on the naked body (sometimes also on clothes). [this belt is made of] wolf’s leather or human skin, especially the skin of a hanged man, often adorned with the zodiac, and with seven tongues on the buckle [which must be put] into the ninth hole; if they want to return to their human form, they open the buckle.”
Wolf Girl Night