Beswick synthetic sapphire orifice (also known as flow restrictors) are ideal for instruments requiring extreme precision and consistent flow rates.  Sapphire is almost as hard as diamond. It is wear, heat and corrosion resistant. The orifice is manufactured to exacting tolerances. Hole diameters as small as 0.003 inch and as large as 0 .021 inch can be ordered in increments of 0.001 inch diameter. Available in brass, 303 & 316 stainless steel.  The maximum pressure rating is 250 psig (17.2 bar).