A trolley for a rail , the trolley comprising: a frame ; a set of wheels , including a first wheel and a second wheel , rotatably coupled to the frame ; and an attachment member , coupled to the frame , for attachment, preferably suspension, of a load therefrom, in use; wherein the first wheel is rotatable in a first plane about a first axis and the second wheel is rotatable in a second plane about a second axis; wherein the first plane and the second plane define a line, wherein the line is the intersection of the first plane and the second plane; wherein the attachment member is arrangeable in: a first configuration, wherein the attachment member is arranged at a first angular displacement about the line; and a second configuration, wherein the attachment member is arranged at a second angular displacement about the line, wherein the first angular displacement and the second angular displacement are different; characterised in that : the trolley comprises a guide coupled to the frame , arranged to guide the attachment member between the first configuration and the second configuration; wherein the attachment member comprises a roller arranged to roll on the guide , wherein the roller is a grooved roller and/or wherein the guide has a circular-cross section. a frame ; a set of wheels , including a first wheel and a second wheel , rotatably coupled to the frame ; and an attachment member , coupled to the frame , for attachment, preferably suspension, of a load therefrom, in use; wherein the first wheel is rotatable in a first plane about a first axis and the second wheel is rotatable in a second plane about a second axis; wherein the first plane and the second plane define a line, wherein the line is the intersection of the first plane and the second plane; wherein the attachment member is arrangeable in: a first configuration, wherein the attachment member is arranged at a first angular displacement about the line; and a second configuration, wherein the attachment member is arranged at a second angular displacement about the line, wherein the first angular displacement and the second angular displacement are different; characterised in that : the trolley comprises a guide coupled to the frame , arranged to guide the attachment member between the first configuration and the second configuration; wherein the attachment member comprises a roller arranged to roll on the guide , wherein the roller is a grooved roller and/or wherein the guide has a circular-cross section. a first configuration, wherein the attachment member is arranged at a first angular displacement about the line; and a second configuration, wherein the attachment member is arranged at a second angular displacement about the line, wherein the first angular displacement and the second angular displacement are different; characterised in that : the trolley comprises a guide coupled to the frame , arranged to guide the attachment member between the first configuration and the second configuration; wherein the attachment member comprises a roller arranged to roll on the guide , wherein the roller is a grooved roller and/or wherein the guide has a circular-cross section. the trolley comprises a guide coupled to the frame , arranged to guide the attachment member between the first configuration and the second configuration; wherein the attachment member comprises a roller arranged to roll on the guide , wherein the roller is a grooved roller and/or wherein the guide has a circular-cross section. <EOS>