Each Classic pop up flavour recipe is the same as the corresponding boilie recipe so it is much more natural to the carp to eat the hook bait when they are feeding on the free offerings.
The flavour levels are however higher than the standard boilie and work similar to a dipped bait, drawing carp to the hook bait.

The 15mm and 20mm Classic Airball pop ups are made with a blend of boilie mix and Airball Pop up mix to balance perfectly with a size 6 hook and the equivalent of a single BB shot to make critically balanced pop up rigs. The little 10mm pop ups need to be used with smaller hooks but are much more buoyant for their size with no added boilie mix and make brilliant snowman rigs used with a 15mm bottom bait.

Nashbaits Airball pop ups can be either tied on or pierced with a needle and mounted on a hair rig in the traditional manor. The buoyancy comes from the base mix and not a cork insert. The base mix is designed to take a little water in and to swell up slightly to let the flavours and food signals leak out into the surrounding water and to tighten up tied on pop ups to ensure small fish can’t knock the bait of if tied on. A little trick if you tie pop ups on is to soak the tied on rig for a few minutes so the pop up swells to tighten the knot and avoid loosing the hook bait on the cast.

(Please note image used is of 10mm baits)