Blue-White Industries F-40750LN-12 Acrylic Flow Meter 3/4" Adapter F/NPT are machined of high-quality annealed acrylic and polished to a clear finish. Scales are screen printed on the meter body with a white back reflector for easy reading. Adapters are Polypropylene reinforced with aluminum stress rings for added strength, and o-rings are FKM.