Dava
I love the look & feel of these though haven't had any eperience playing with different ones. They're a nylon Grip Tip using their patented over-molding & multi-gauge flexibility. By adjusting your grip you can vary the gauge. Also available in Delrin & Poly Gels. Would like to get some more to put on here.
Dava Control by Dave Storey. Introduced in 1996, the Dava Control features a flexible middle so you can vary the gauge while playing, just by varying your grip. This is one of the early models and is made from Nylon.