Each combo pairs one OPI Intelli-Gel color with the Intelli-Gel Super Base Coat and the Super Gloss top coat named in the listing title, so one order covers a full gel service in a single shade. The color code in the title tells you which shade is included, and the same code is used on the single Intelli-Gel bottle, so reordering a favorite color later is simple.
A 3 in 1 set gives one OPI shade code in three formats: Powder Perfection dip powder, Intelli-Gel gel polish and Nail Lacquer. A salon can then offer the same color as a dip, a gel manicure or a lacquer pedicure without matching shades across brands. The shade code in the title is the same on all three formats.
Not necessarily. On DTK the combos and sets are priced at the same rate as the single items they contain, so they are a convenience, not a price break. Compare the bundle with its pieces before ordering if price per bottle matters to you, and check each listing for stock, since many combos sell out between restocks.
Intelli-Gel cures in about 30 seconds per layer under an OPI Star Light lamp or about 2 minutes under a UV lamp. Apply the base, then two thin color coats and the top, curing each layer. Thin coats cure evenly and wear better than one heavy coat, and capping the free edge on each layer helps the color last.
OPI describes Intelli-Gel as HEMA-free and TPO-free. HEMA-free does not mean a client can never react to a gel, because other acrylates can still cause sensitivity, so a patch test is wise for clients with a history of reactions. Older GelColor bottles are a different formula, so read each label before you recommend a bottle to a sensitive client.