Unblock Series manhole cover unblockers unblock covers which are especially difficult to open due to tar, frost, asphalt, salt and sediment deposits on the point of contact with the frame. The action of the tie rods creates tension, which causes the deposits to break down. Once the cover has been brought back to its natural weight, it will be possible to intervene with a manhole cover lifter. They are supplied together with a set of useful accessories for removing dirt from manhole covers. UnBlock-30 is equipped with a series of single keys and is suitable for unblocking small manhole covers and drain grates. The cover is anchored to a single attachment point located near the edges (max. 30 cm). UnBlock-80, -100, and -120 are equipped with interchangeable pairs of keys and can also hook the manhole covers simultaneously on two points. The number that follows UnBlock indicates the maximum width in centimetres of the manhole covers to which they can optimally adapt. The -R (Reinforced) versions have increased load capacities.