The SL30 Speedline chalk line has a quick rewind function which is around three times faster than the AL30. It has a casing made of hard and durable polystyrene plastic with a sliding filler cover.

The cord is braided cotton/polyester, the cotton absorbs the chalk, the polyester provides the strength and the braid ensures that the cord never tangles. The cord is 1mm in diameter and has a rupture limit of 16kg and can contain 100g of chalk.