Pilot Spotliter VW | This two-color highlighter marker has a visible ink tank that allows you to track how much ink you have left. You can see the liquid ink swish around
Pilot Spotliter 2 Double-Sided Highlighter Pen - Broad / Fine Twin Tip - Purple | JetPens
Pilot Spotliter Supreme Highlighters - Chisel Marker Point Style - Fluorescent Yellow - White Barrel - 1 Dozen