A ladder is provided having a base section and a fly section slidably coupled with the base section. The base section includes a first pair of spaced apart rails and a first plurality of rungs extending between and coupled to the first pair of spaced apart rails. The fly section includes a second pair of spaced apart rails and a second plurality of rungs extending between and coupled to the second pair of spaced apart rails. The various rungs may be coupled with their associated rails in an offset relationship such that they are not centered along a longitudinal center axis line of the rails. A rung lock device may be used which includes an arm pivotally coupled with the base section and configured to selectively engage various rungs of the second plurality of rungs to maintain the fly section in a desired position relative to the base section.