GLA-5000 PVC membrane disc filters, a Pall Life Sciences product, are inherently low ash membranes. Assures gravimetric stability with low moisture pick-up and low tare weight. Low ash. Provides interference-free silica determinations. 25 and 37 mm sizes are ideal for use in Air Monitoring Cassettes. Applications Excellent membrane choice for sampling airborne metals, silica, and dust.