A counter (203) comprising: a first ring member (201) having first marks (701) and a second ring member (202, 1510) having second marks (702), each of said first and second being rotating ring members in increments around a common axis (214), indicating one or both of said first and second marks a count； and a drive mechanism (205) for rotating said first ring member and for rotating the second ring member after one or more predetermined degrees of rotation of the first ring member； wherein said dragging mechanism comprises a ratchet and teeth mechanism comprising a first and second ratchets (402a, 402b) applicable with a plurality of teeth (210)； and wherein each of said first and second ratchets comprise a drag application face (440) for application in a drag application with one of said plurality of teeth, and a sliding application face (430) for sliding on one of said plurality of teeth, and. wherein each of said first and second ratchets (402a, 402b) is arranged such that: said first ratchet is applied in a drag application with one of said plurality of teeth during a counting stroke of said teeth, and said second ratchet is applied in a drag application with one of said plurality of teeth during a return stroke of said teeth, and said second ratchet slides over one of said plurality of teeth during said count stroke, and said first ratchet slides over one of said plurality of teeth during said return stroke.Un contador (203) que comprende: un primer miembro de anillo (201) que tiene primeras marcas (701) y un segundo miembro de anillo (202, 1510) que tiene segundas marcas (702), siendo cada uno de dichos primer y segundo miembros de anillo giratorios en incrementos en torno a un eje común (214), indicando una o ambas de dichas primeras y segundas marcas un recuento； y un mecanismo (205) de arrastre para hacer girar dicho primer miembro de anillo y para hacer girar el segundo miembro de anillo después de uno o más grados predeterminados de rotación del primer m
