--3x7 Gridfinity standard. --251 x 90.5 x 12.5mm-- cavity incase it fits other brands of boxes. --No walls so the lid can be opened without removing the box from the holder. --I reccomend keeping the box stored cracked open as its a hassell to open the box. --Prints in 2 halves to accomidate the bed size of most printers. ............. I didnt like the idea of having my calipers standing up and possibly getting knocked over and getting dirty being in the open like other calipers holders, so I designed this holder that holds the box that came with the General Calipers I got from Ace Hardware.