In case the old physics work bench is in need of repair but you don't know what size bolt is needed we have the perfect solution. A pack of 5 different sized steel bolts. Actually the different bolts provide not only a nice systematic way to conduct experiments needing different sized masses but they also fit into any budget. These work well with the water displacement method for finding the volume of an irregular object. Besides try fixing that old bench with a set of hooked masses.