marker tip protection. resistant-tipped fluorescent marker that doesn't smear on rulers. The polymer coating found in Kei Coat's core keeps the marker tip from breaking, leaving uneven lines, or discoloring rulers—all of which could cause the marker to bleed onto nearby surfaces and the tips of other pens. Highly resistant polymer coating protects the core and greatly reduces frustration caused by pen tips. Each and every usage is guaranteed to be precise and tidy. You can use a single marker for a longer period of time and save money by using the refill "Kei Coat Charger." Clean, resistant tip that maintains rulers The polymer-coated core's resin coating keeps the marker tip from shattering and discoloring rulers. Unique polymer core (fine core)