I'm awaiting a set of pro-loks that i want to test out. Since the guy is a startup he makes them as a side job for his outfitting business. So i should be getting them any day now (rolleyes
They are similar concept to the posilocker system but the horn is stainless and they use some sort of plastic sleeve that slides along your shaft and pops off the horns if you really overstress the system (catastrophic).
I think the sleeve is a greasy type of bushing material that has low friction against your bare shaft.
The nice thing appears to be you can still easily feather or you can do a locked position like the grant's oar rights
And judging from the pics i can get an additional inch or two from my existing towers, or keep the same height and feather the angle out on my towers to get more balance in shaft weight. There is a limit to how much you can do this (angle) with the cobras. Plus you lose height when the towers are not normal to the shaft.
And the stainless should be stronger than any brass oarlock (i've had one cobra bend at the shaft)
The cost of them is comparable (favorably) to a set of cobras, a sleeve/wrap, and some sort of oar lock. I think they even have a cable which replaces the need for tethers although i'll stick with mine.
I've got some used cobras i'd probably sell once i get the pro-loks. Pm me if you are interested
By the way, nice boat!