There are 3 drilling angle of 30 degree, 45 degree and 90 degree, And four sizes of guide holes for each drilling angle, which are 3/8”(9.52mm), 5/16”(7.93mm), 1/4”(6.35) mm), 3/16"(4.76mm), It is specially design for cable railing kit lag screw fitting post installation.The drill guide is made of industrial grade aluminum alloy are machined by precision computer numerical control, and the guide holes of this drill guide is upgraded to an inlaid steel drill sleeves, which will not wear out and lose precision after multiple drillings. with a CNC anodized surface, wear-resistant, and corrosion-resistant.The drill hole guide jig is easy to use and carry. Ideal for wood, aluminum or stainless steel for household office DIY projects, high precision woodworking endeavors where precise drilling angles are necessary for a clean and accurate finish.90 degree V-groove can be drilled at 90 degree corner and cylindrical surface. This drill guide can be used in conjunction with locking C-clamp and F-clamp to prevent the drill guide from shaking when drilling, and the drilled holes are free of burrs and cracked. It is suitable for the installation of wooden, aluminum, and stainless steel deck posts for cable railings and DIY woodworking projects. (F clamps and C clamps are not included).This drill guide is equipped with four size of titanium-plated drill bits, corresponding to four sizes of pilot holes, to achieve simple and convenient precise drilling. It can be used in conjunction with locking c-clamp and f clamp to prevent the drill guide from shaking when drilling, and the drilled holes are free of burrs and cracks.