SONY: ND15G, ND15 A, ND15 G, ND25 E, ND25 G, XL15, XL15 A, VL15 G, XL25, XL25. STYLUS Model: ND15G. The two most common stylus shapes are spherical (conical) styli and elliptical styli (bi-radial). A typical conical stylus tip (similar to a ball point pen) has a larger radius (compared to an elliptical stylus).