A portable service table is moveable between a closed configuration and an open configuration. The portable service table includes a tabletop, a first leg assembly attached to the first portion, and a second leg assembly attached to the second portion. The tabletop has a first portion and a second portion. The first portion has a first portion top, a first portion bottom, and defines a steering wheel recess that extends from the first portion bottom toward the first portion top. The second portion is hingedly attached to the first portion. The second portion has a second portion first end, a second portion second end, and defines a second portion handle and a second portion passageway. The second portion handle is defined on the second portion second end. The second portion passageway is adjacent the steering wheel recess when said portable service table is in the closed configuration.

A gravity-actuated locking structure includes a locking buckle and a rotation shaft assembly. The locking buckle includes a position-limiting member, and the rotation shaft assembly includes a position-limiting matching member configured to be matched with the position-limiting member. When the gravity-actuated locking structure is placed in a first orientation, the locking buckle swings to a first position relative to the rotation shaft assembly due to gravity, so that the position-limiting member and the position-limiting matching member are interlocked with each other in a rotation direction of the rotation shaft assembly. When the gravity-actuated locking structure is placed in a second orientation, the locking buckle swings to a second position relative to the rotation shaft assembly due to the gravity, so that an interlocked connection in the rotation direction of the rotation shaft assembly between the position-limiting member and the position-limiting matching member is released.

A multi-size folding table with a stable structure is provided. A table board includes a middle table board and two side table boards. Two ends of the middle table board are respectively pivotally connected to the two side table boards. The two side table boards are configured to be rotated to achieve unfolding and folding thereof. A bottom surface of the table board is correspondingly disposed with guiding members. The guiding members are respectively connected to four table leg assemblies. The four table leg assemblies are configured to reciprocate. Each of the four table leg assemblies includes a supporting leg for supporting the table board. When the two side table boards are in an unfolded position, the supporting legs are located below the two side table boards. When the two side table boards are in a folded position, the supporting legs are located below the middle table board.

One or more devices are provided that are configured to detachably engage within a modular system. The one or more devices are expandable to provide a surface to perform work.