Elesa® original design technopolymer plastic dome-shaped fluid level sight glasses. Mainly used as oil circulation indicators. Practically indestructible; even if high torque is applied there is no danger of breakage. Resistant to aging, not alcohol resistant. Because of the high strength of the material (considerably stronger than, for example, Plexiglass), these sight glasses can be produced with much thinner walls, resulting in clearer visibility. The ratio between bore diameter and the viewing window is much improved. A moderate torque (not exceeding 3-12 Nm) is recommended when tightening oil sight glass so as to guarantee optimal tightness without any elastic deformation. Full details regarding torque available upon request.