Put the pleasure in prostate training as you gradually work your way through these super soft silicone probes, and enjoy the delicious massage each individual piece has to offer. An additional buzzing stimulator makes it the only anal investment you need. The prostate probe with ring measures 3 insertable inches and 4. 75 in circumference. The beaded prostate probe measures 3. 75 insertable inches and 3 inches in circumference. The smaller prostate probe measures 3. 5 insertable inches and 3. 5 inches in circumference. Slather with a good quality water-based lubricant and begin your training session.