RX8247V is the prescription version of the round-fronted 8247, sharing the same 145mm metal arm length as its sunglasses counterpart. This aftermarket pair matches that length and the round curve into the hinge, so it fits the eyeglass version specifically rather than a shorter 140mm arm pulled from a different Ray-Ban line. Since the sunglasses RB8247 uses the identical shape and length, the RX prefix here is the detail that actually distinguishes the order.

Because the sunglasses and eyeglass versions of the 8247 share dimensions, it's tempting to assume any 8247 arm will do — but confirming the RX prefix and the 145mm length before ordering avoids ending up with an arm that's a close guess rather than an exact match. Eyeglasses also tend to see more daily handling than sunglasses, so the hinge on a frame like this is worth checking for play a little more often.