Review on DEWALT DW5237 18 Inch Premium Percussion by Erik Snyder

If you need to drill at least one foot in concrete, this drill bit is great for using the pilot hole technique: Bluntly drill a pilot hole through the other end of the wall, then use smaller bits of the desired diameter to drill up one side and then thread the other side along the drilled pilot hole until the lengths meet, giving you the desired hole diameter measurement. You can use a regular 8 inch concrete drill bit. After all, 8 x 2 is 16 inches and an average of 4 inches less than the usable length, you can drill through a 12 inch (1 foot) thick concrete wall.