Na12[(AIO2)12(SiO2)12] • X H2OMolecular Sieve Type 4A, the sodium form of the Type A Crystal structure, is an alkali metal alumino-silicate. Available in powder, pellets, mesh and beads for static dehydration in a closed gas or liquid system. Used in packaging of drugs, electronic components, and perishable chemicals; and as a water scavenger in paint and plastic systems. Type 4A is also used commercially in drying saturated hydrocarbon streams.The sizes of both Mesh and Beads are specified jointly by the screen sizes that the material will pass through and retained by. For example, a 14 x 30 mesh product will pass through a 14 mesh screen, and be retained by a 30 mesh screen. Listed below are the screen openings for some common screen sizes.