They probably just slide up behind your ear on the stem to keep the glasses in place. Dont think Oakley makes them but that doesnt mean you cant use them.
They're not made by Oakley and wouldn't have been included by Oakley but perhaps by the retailer. They hit stores in the 90s when more and more Oakleys and a few other brands moved to the straight earstems or for earstem on styles that were too long and overshot the ears.