I am exited to release these new nipples. I designed them to hold up to the aggressive nature of hard hitting machines such as my Sidewinder and Swingliner. Made from the most durable rubber I could find. They are firm, but not as hard as the Hard Black Nipples. They have a tapered inside diameter, so as it is pressed onto the post the nipple spreads itself around the needle loop for a secure fit. My favorite part of this style of secure fit is that the nipple isn't stuck to the needle when removing it from the machine. My intent for that was to get more use out of them, and reduce waste.