One shade, produced in more than one format
A duo is a single shade made in two formats, gel polish and the matching lacquer, sold under one name. A trio adds the dip powder in that same shade. This page gathers those matched sets, with DND duo gels and OPI season collections among what is listed.
What a matched set solves at the station
When a client books gel on one visit and regular lacquer on the next, a matched set means the same shade carries across both services, and nobody is holding two bottles up to a lamp trying to call it close enough. It helps on the retail side too, since the color on the hand and the bottle on the shelf belong to the same product family. Buying the set also settles which formats you can offer in a given color before the question comes up at the station, rather than after a client has already picked the shade off a display.
Building the order
Sets here span more than one vendor, so this is a reasonable page for comparing a DND duo such as 430 Ferrari Red against an OPI season collection without switching grids. If you want the dip step included, trios is the narrower list. For gel and lacquer pairs on their own, begin at gel and lacquer. Brand-first shoppers can go straight to DND or OPI. Sets ship in one to two business days, standard transit is two to five business days, and there is free shipping on orders over $150 within the 48 contiguous states, which leaves room to cover a seasonal shade refresh in one order rather than splitting it across a month.