The Buck-Off was designed specifically for transmen well into transition, so Buck-Off came out with Kiss-X to fit transmasc folks not in medical transition or who may be early on in their HRT. It's snugger and has a different shape at the base. The KISS-X is a purposefully designed suction stroker to fit over the clitoris, while maintaining the style and benefits of the Buck-Off. Made of SilaSkin, a TPR/Silicone blend. Use with a water-based lubricant.