2200-12500Pcs Bee Hive Copper Eye Beehive Threading Hole Size: hole inside diameter of 1.5 mm * Length 4 mm Description: After the nest box mounted on the copper wire eye eye, you can prevent the wood too tender, leading wire embedded in the nest box, resulting in deformation of the nest foundation. Note: Size for manual measurement, there may be a 0 to 2 mm error, belongs to the normal phenomenon. And due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!