Since duo-grips cross chains are connected in the middle, this pattern does not fall between the tread bars. Duo-Grip Tire Chains recommended for: field work deep tread off road use hilly conditions Not recommended for use on pavement. Duo Style tire chains may dig blacktop or concrete more than the ladder style. Since it has chain running in the circumference as well as side to side it provides unparalleled lateral stability. Normally, there are more cross chains per side on a Duo Grip tire chains than on any other pattern of snows chain (double or ladder). For example, A 14.9-28 duo has 22 cross chains. A 14.9-28 ladder snow chains only have 16 cross chains. In most sizes, also available in a V-BAR version. Which is perfect for ice and hard packed conditions. V-BAR Duo-Grip Trip Tire Chains cost effective alternative to bull ring and Canadian style chain.