The GWL lathing washer is designed for use with both the new G3 gas-actuated fastening tool and the former GCN-MEPMAGKT gas-actuated concrete nailer tool to attach lath to the wall surface for overlaying scratch coats, brown coats, and stucco. These washers are held onto the single-shot nosepiece of either the G3 or the GCN-MEPMAGKT with the magnetic ring (model G-422, replacing the GMR-2). The washers attach to concrete or CMU substrate with gas-driven pins (GDP), which fasten through the washer.