Yakima StageTwo Plus 2 Platform Rack Add On - Anthracite NoAusPost the other a lens optimised

the other a lens optimised for wide beam

this stainless steel cog from Wolf Tooth is the answer

and 6mm hex set

Compatible with all forward and double bridge fork designs

Cons: The only con that comes to mind is why they didn't extend or have a secondary exterior plastic guard featured on the knee cap to increase durability further

Yakima StageTwo Plus 2 Platform Rack Add On - Anthracite NoAusPost the other a lens optimisedThe StageTwo +2 Add On takes your Yakima StageTwo from a 2 bike platform style carrier to a 4 bike beast. The StageTwo +2 Add On continues the upwards trajectory of the main support arm that extends from your vehicle's 2" square receiver, affording you a little more ground clearance. This design also provides both horizontal and vertical offset to the bikes on the carrier which provides even better bike separation and lowers the possibility of contact