GH1838 has a raised surface finish. It is frequently used for fencing panels where difficulty in penetration is important.
The LWM (Long way mesh) is across the sheet while the SWL (Short way length) is along the length of the sheet. Thickness is the thickness of the sheet being used to cut the mesh from. The strand is the width of each slice.
For more specific detail about Gridmesh including loading specifications please follow this link to Gridmesh Technical.