hmm the only ones i've seen here are 50 and 100W HPS versions with the rounded lens. The distribution is better with this lens but it might be because the lens isn't clear anymore. the tint is probably what makes the light more even (and it's dimmer too). The funny thing is, the light is distributed more evenly with no lens than it is with the round plastic lens.
I've also seen a few M-250R2 with these lens. I have personally never maintained one of these since my utility never used these fixtures. The only cooper/crouse hinds fixtures we used was the OVM.
ahh here the OVC was the only one used on wood poles. the OVS and OVM were used with RIDOT's first relay installations with davits on the freeways. OVSs in 250W on the ramps, OVMs in 400W on the freeway. In old Blackstone Vally Electric, there are one or two OVMs on wood poles in 250 and 400W. In Attleboro in old Mass Electric Co territory, the OVC is around in 50 and 100W HPS on side roads with the rounded lens and larger roads like Rte 123 use the OVS in 100W HPS with either glass or the squared plastic lenses.not sure why they used both for the same wattage and one used plastic and the other likely used glass. The only thing i can think of is that the OVSs were installed before the OVCs.