Ru?t g?i: ???c làm t? Cao su non t? tr?ng cao. ?? b?n t? 5-seven n?m, v?i ?? ?àn h?i ch?m nâng ?? c?t s?ng???c c?i ti?n t? th? h? ??u, th? h? th? 2 thi?t k? chu?n cho c? 3 t? th? n?m: n?m ng?a, n?m nghiêng hay n?m s?p.Th? h? th? two ????c thi?t k? c?i ti?n t? th? h? ??u. Gô?i phu? h??p cho c? three t? th? n?m: n?m ng?a, n?m nghiêng hay n?m s?