Sand Gauge chart .
Sand Gauge has nine granule patches which are firmly attached to the handy 3.5x2.5in (89x64mm) water-resistant plastic card to assist in defining roundness and size of particles from 2mm very coarse sand to 1/16mm silt. A checklist is included to assist in making field notes and defining bed thickness. Flip side of chart has tables of geologic age and carbonate classification information. Model HM-513 has a 0—50mm scale on one edge and an attached lanyard.