Sink tips and polyleaders can be added to the ends of Skagit, Scandi, or even traditional fly lines to give you the ability to transform it into a sink tip or make it a longer version of a floating line. Sink tips generally have a line weight or grain weight associated with them, while polyleaders (aka versileaders) are not rod weight specific. Sink tips are built on a braided core and are thick like a fly line, while polyleaders are built on a mono core and are thin and light.