Quality product from ALIGN Corp. Ltd. Specification - Linkage ball A (M2.5x3.5) x 4 (Ø4.75x8.18mm) - Linkage ball B (M2.5x3) x 2 (Ø4.75x9.77mm) - Linkage ball D (M3x3.5) x 2 (Ø4.75x17.5mm)