Pentair PVC Small Niche for Concrete Installation per SpaBrite and AquaLight Light – Gunite plastic niches are plastic concrete niches are molded of high strength, corrosion resistant PVC with a one inch PVC hub. Both 450 and .75″ reducer bushings are included. Gunite models feature rebar tie-backs and a plaster ring for clean, simple installations and all are packed with a gunite per plaster shield.