The double blade system, more commonly known as the “Baht Chaum Dou” (Eight Chop Knives), focuses on the parallel (or double) blade techniques that Yip Man learned from his teacher Leung Bik. Yip Man then taught Wong Shun Leung. Wong passed the system to his student of 25 years, Yeun Yim Keung. Before his passing, Master Yeun passed on the blade system to John Di Virgilio and others.