Made of precision-cast AISI 316 stainless steel.Constant torque 30 kg·cm ± 15% guaranteed for 20,000 cycles.The torque is expressed in kg·cm,, meaning that departing from the hinge rotation axis, the effort decreases.Torque calculation: hatch depth (cm) x 1/2 hatch weight (kg).Example: 2x 30-kg hinges perfectly hold a hatch 2-kg heavy and 40 cm deep.