The Self Lock Speed Mark Series of tape measures is a unique line of tape measures. The series features 12-foot x 5/8-inch, 16-foot x 1-inch, and 25-foot x 1-inch. The Self Lock Speed Series features a unique self locking mechanism that allows the blade to extend smoothly as well as a push button release that insures complete control when retracting the blade. This series also provides printed fractional graduations for easy read and accurate measurements. This is the ideal measuring tool for anyone from the do it yourselfer to a professional tradesmen. This tape measure also has a nylon coated blade for maximum durability.