AMAZON CHOOSES COLOR. NO BATTERIES or CALIBRATION. | MORE POWERFUL THAN THE COMPETITION: The StudPoP's unique design makes it much more SENSITIVE than ALL other magnetic stud finders, making it ideal for ANY construction type, including challenging surfaces like LATH & PLASTER and TILE. | DON'T BE FOOLED: All other magnetic stud finders only work on SHEETROCK. But the StudPoP will work on SHEETROCK, LATH, PLASTER and TILE! | FORGET ABOUT THE ELECTRONIC ONES: They depend on unreliable batteries and a clumsy calibration procedure and they almost NEVER work on LATH & PLASTER. Bottom line: most of them aren't very good at anything :( | FUN & EASY TO USE: The StudPoP makes stud finding FUN with its 1" diameter moving magnet that gives an audible click and a visual movement when a fastener is found. It doesn't get any easier than this! | PERFERRED BY OWNERS OF OLDER HOMES: Because of the way walls were done in the "olden days", the StudPoP is the go-to stud finder for folks with those IMPOSSIBLE walls.