Staedtler make a range of top quality highlighters. The classic Textsurfer is refillable, making it better for the environment and your pocket - a great choice if you highlight a lot. The Textsurfer Gel is an unusual one - smooth gel, almost like highlighting with a lipstick, but it's really good to use; and the Textsurfer Dry is a handy highlighting pencil, with no ink to dry out - both of these are perfect if you forget to put the cap on - they won't dry out while you're thinking!