Filaments of glassfibre, bundled loosely together to make a thicker string. These strings may be woven into a cloth which is known as Woven rovings, which can be used as reinforcement for polyester resin in hull construction. Although woven rovings is a very strong material, Chopped strand mat is often preferred because it is difficult to get woven rovings to absorb sufficient resin. A mixture of the two types of reinforcement can be very effective in certain cases.