Automatically lock the spring at maximum extension, with a simple movement the sliding is released. This safety device is recommended to prevent a door from inadvertently closing in the event of rolling or pitching. Body made of AISI 316 stainless steel. N.B.: 1) By adding the lock, the declared length of the spring extends by 25 mm. 2) In case of installation in pairs, order extension 38.040.90.