The EP004K is designed for use with guitars that have pinless bridges and/or a center brace. (like a Torres classical guitar) If you have a 6 string guitar that does not have a center brace and regular pin holes, we recommend the EP001K as it's easier to position the piezo elements, and the additional sensitivity from the extra piezo on this model is minor.  If you're using the 4 piezo model on your guitar with no center brace or with a pinless bridge, however, we recommend positioning the piezos equidistant along the bridgeplate under the saddle so that on the 1st and 6th strings the piezo element extends about 4 mm beyond the center of the strings. If this extends beyond the bridgeplate or you don't have room, you can simply line them up as evenly as possible on the bridge plate so that they fit. You can allow for a maximum of 3 mm overhang if your bridgeplate doesn't have enough room. It's impossible for us to give  precise positions on this because there are so many variations on bridge plate sizes and string spacing. For detailed instructions, click here: https://journeyinstruments.com/pickup-installation-manuals/