Use this bad boy as a plug and p-spot vibrator!
The Onyx excels both as a plug and as a prostate massager. It's smooth silicone is rendered into delicious curves that will feel great as they slide into you. Once it's in, it has a neck for your butt to clamp down on and hold it in place. Thanks to the anchor shaped base it will feel comfortable between your cheeks without any danger of getting lost.
Of course once you have it in, it makes a great prostate massager. It's well curved to rub up against your prostate. You can use the head of the bullet as a handle to rock it back and forth. Since it has a long bullet you can expect more of the vibrations to reach the tip, which is where you want them.