Sight glass, Oil level sight glass, liquid Sight Glass, Oil level indicator, ViewportMaterial Body: Aluminum, Steel and Brass O-Ring: Viton and NBR Glass: Real Glass Glass Thickness: 2mm to 5 mm Glass Type: General Glass, Tempered Glass and Borosilicate Glass Resist Temperature Range:-30\' to 120\' Size: M10X1,M12X1.5,M14X1.5,M16X1.5,M20X1.5,M24X1.5,M27X1.5,M42X2, G 3/8,G 1/2,G 3/4,G 1 NPT 3/8, ...