A counter comprising: a first ring member having first indicia and a secondring member having second indicia,each of said first and second ring members being rotatable in increments abouta common axis, one or both of said first and secondindicia indicating a count； a drive mechanism for rotating said first ringmember； and a coupling mechanism for releasablycoupling said first ring member to said second ring member, to allow saidfirst and second ring members to rotate cooperativelywhen coupled and to allow independent rotating of said first ring member whennot coupled； wherein said coupling mechanismcomprises first and second engagement means, said first engagement means beingmovable radially outwardly and radially inwardlyrelative to said axis.
