A grid-based storage and retrieval system comprising: a grid framework structure comprising: a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicularly to the first set of rails or tracks in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces, a load handling device comprising: a body mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; and, a lifting assembly (180, 190, 200, 240, 250) comprising: at least one hoist drum (184, 194, 251); a gripper plate; the grid-based storage and retrieval system further comprising a centralised control utility for controlling the at least one load handling device; characterized in that the load handling device further comprises a sling assembly arranged to support, raise and lower a load, the sling assembly comprising a sling extending between a support mountable to the body of the load handling device and the gripper plate for supporting the load, wherein first and second ends of the sling are attached to the at least one hoist drum (184, 194, 251). a grid framework structure comprising: a first set of parallel rails or tracks and a second set of parallel rails or tracks extending substantially perpendicularly to the first set of rails or tracks in a substantially horizontal plane to form a grid pattern comprising a plurality of grid spaces, wherein the grid is supported by a set of uprights to form a plurality of vertical storage locations beneath the grid for containers to be stacked between and be guided by the uprights in a vertical direction through the plurality of grid spaces, a load handling device comprising: a body mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; and, a lifting assembly (180, 190, 200, 240, 250) comprising: at least one hoist drum (184, 194, 251); a gripper plate; the grid-based storage and retrieval system further comprising a centralised control utility for controlling the at least one load handling device; characterized in that the load handling device further comprises a sling assembly arranged to support, raise and lower a load, the sling assembly comprising a sling extending between a support mountable to the body of the load handling device and the gripper plate for supporting the load, wherein first and second ends of the sling are attached to the at least one hoist drum (184, 194, 251). a body mounted on a first set of wheels being arranged to engage with the first set of parallel tracks and a second set of wheels being arranged to engage with the second set of parallel tracks; and, a lifting assembly (180, 190, 200, 240, 250) comprising: at least one hoist drum (184, 194, 251); a gripper plate; the grid-based storage and retrieval system further comprising a centralised control utility for controlling the at least one load handling device; characterized in that the load handling device further comprises a sling assembly arranged to support, raise and lower a load, the sling assembly comprising a sling extending between a support mountable to the body of the load handling device and the gripper plate for supporting the load, wherein first and second ends of the sling are attached to the at least one hoist drum (184, 194, 251). at least one hoist drum (184, 194, 251); a gripper plate; the grid-based storage and retrieval system further comprising a centralised control utility for controlling the at least one load handling device; characterized in that the load handling device further comprises a sling assembly arranged to support, raise and lower a load, the sling assembly comprising a sling extending between a support mountable to the body of the load handling device and the gripper plate for supporting the load, wherein first and second ends of the sling are attached to the at least one hoist drum (184, 194, 251).