The marks here are a custom series, registered with ApexCharts.registerSeriesType('ringStem', { dataType: 'rangeXY', renderItem }). (For the ordinary two-dot version of this chart, ApexCharts has a built-in chart.type: 'dumbbell'; this is what to do when you want a mark of your own.) renderItem draws one stem and two circles per datum through the primitive api, and dataType: 'rangeXY' routes the y: [start, end] pair through the range path so the y-axis fits both bounds and the tooltip reads "start - end". Hover a marker to see it.