Good question, Penny! It takes 3 round Lithium-Ion batteries that loook like watch batteries - only thicker - they go in stacked - I included them in the torchlight so you would know the exact ones to replace. These are available at Walmart or at most CVS or Walgreens. Thanks for asking!
Thanks! As a layout engineer working on hi-rise projects, I found it useful in locating oft unnoticed cracks in concrete - but there's many other uses as well.