When I got my Westone custom molds, they came with a sample packet of Oto-Ease, also made by Westone. I put a drop on the left mold, which is the one that’s harder to insert because of a smaller, curvier ear canal, and rub any excess off on the right mold. I’m careful to put it on the molds behind the opening to the receiver and the wax guard. Bottle says “sterile, water soluble, greaseless, unscented.” The Costco audi said if I liked it, she’d get me more, but Amazon sells it, so I just ordered it there.