Hannun gwiwar digiri 90 nau'in gwiwar hannu ne mai kusurwar digiri 90, galibi ana amfani da shi don canza yanayin tafiyar bututun. Yawancin lokaci ana amfani da shi a cikin tsarin bututun mai inda ake buƙatar matsananciyar lanƙwasawa, kamar lokacin da ake buƙatar haɗa wasu kayan bututun kafin ko bayan lanƙwasawa.
