9-Piece Metric Hex key size: 1. 5mm, 2mm, 2. 5mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm. Hex Hey has size marking printed on the body for easy identification. Plastic holder plastic holder firmly retains each Key in the hole. Multi-use: suitable for installing towel bars, repairing bicycles and assembling furniture.