Can't help you find the prop, but FYI you don't need one.

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2719482

These are all done with the shader provided in the linked thread. You apply the shader directly to the legs (and hip). If your figure doesn't have a separate material zone for these areas, you can quickly make one using the Poser Grouping tool. It's all shown in the thread.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)