Pure element samples in sealed glass vials. 52 models plus 2 extras. Sodium(Na) attached. Total 52+2+1 units. Can be used for periodic table collections DIY. Don't return if there is broken to the set. If any broken happens to the vials, please don't worry. a. 2 extras are already there for you. b. If the broken is more than 2 pieces, please contact our sales person with pictures, replacements will be shipped for you. Sold by the models, no specific quantity fixed. If you are critical to the exact weight, please contact us before purchasing.