The Oxygene 4 (abbreviated to Oxy 4) is Carlo Menon's follow up to the Oxygene 3. The Oxy 4 introduced the recessed silicone response system. It was sold for $120 to $140. The Oxy4 is well known for its spiral satin finish. Like the Oxy3, it used a titanium axle and was otherwise aluminum. Carlo's first run of these sold out in a matter of weeks. He has made at least one other small run in late 2006. Carlo has mentioned making other small batches, but he doesn't say when or if it will actually happen. Made to be extremely unresponsive, the Oxy 4 was designed for advanced string tricks.