Sentinel is a nice little vibrating plug that's a good size for people new to anal plugs and also for those who prefer the things in their butt to be smaller. The vibrator included is pretty strong, but its vibrations diffuse through the plug, making them a low hum when the plug is inside. Regardless, it's good for experimenting with anal vibrations. Sentinel is made of pure silicone meaning that it is a $40 plug that will last for a long time.
The most helpful critical review
Great Theory, poor performance
Again, another toy that is the greatest design, shape and size with a crappy bullet. This would be so cool if it worked with a rumbling bullet. Anally, I would suggest this for more experienced users.