Abstract: A cam locking and positioning structure is specifically designed form an M-LOK rail and mainly includes a main body for connection with various different devices, and a cam wrench and a tightening axle combinable with the main body. The main body has a through hole, and positioning portions raised from a top thereof. The cam wrench includes symmetrically arranged lugs, and a wrenching part extending from the lugs. The lugs include fixing holes, and rounded projection portions are formed on tops of the lugs. The tightening axle is of a T-shape having a vertical section having an elongated hole. The tightening axle is insertable into the through hole of the main bod, and a pin is inserted into the fixing holes of the lugs of the cam wrench and the elongated hole of the tightening axle to set the cam wrench in a pullable manner.

Abstract: An engagement structure of a connection system contains: a holder, a movable fixer, an actuation protrusion, a connection rod, and an adjustment member. The holder includes a first connecting segment, a first positioning groove, a receiving groove, a rotation space, two coupling orifices, and a locating orifice. The movable fixer includes a sliding portion, a defining portion, a guide groove, a through hole, a second connecting segment, a second positioning groove, and a locking chamber defined between the first positioning groove and the second positioning groove. The actuation protrusion includes a rotatable joining segment, a trench, two first accommodation orifices, two second accommodation orifices, two spaced distances, and a driving segment. The connection rod includes a rotary knob, a threaded section, a rotatable connecting orifice, and a trough. Also, the adjustment member includes a screwing section and a notch.