Brushed Aluminium - Framing Square Attachment for all your framing needs, which might include stair layout, rafter layout, steel framing, or if you just want a cool tool to make your tool bags shine. With this unique cylinder design, and dual slots, there are unlimited possibilities and uses for this framing square attachment. Wood uses - Stair gauges, stair layout, rafter layout, rip guide on your saw, angle guide on your speed square, holds your framing square upright and more! Metal uses - over comes rounded edges on large square tube, easily square up round tube, acts as a third hand when tacking metal together or lining up with a turn buckle, will hang or stand your square up on material and more! Features: Over come extensive wane Rounded corners on square tubing Easy to spot on the job, shop or tool box Easy to use even with gloves on Holds your square upright like a third hand Easier with large pieces then a speed square and much more.. Holds firm by only hand tightened Precision machined Solid Aluminium body with a anodized finish Built to last Made in Portland OR. USA This tool comes as a set, with 2 jigs and the screws. What's the main difference between 15" and 3" framing jigs? The 1-1/4" Tall squijigs are designed for wood carpenters to over come defects in lumber. All though the 1-1/4" squijigs also work for building things like metal hand railing, stairs, truck beds etc. The 3" squijigs on the other hand have a metal fabrication back ground. The 3" weight and size helps the framing square to stay upright and free a hand when tacking parts etc.. Having two slots gives you the freedom to side shift around parts like brackets, welds etc.. Also the larger metal beams tend to have rounded corners and the 3" width easly over comes that. Hope that helps!