There are lots of different manufacturers of modelling balloons, however the most well known is Qualatex. Other makes are Tilly and more recently Sempertex.

Qualatex and Sempertex make very similar products, 160, 260 and 350 (Qualatex), 360 (Sempertex) in a large range of colours, along with other more specialised, but essential balloons like hearts, 321 (Qualatex) and Geo-Blossoms (Qualatex)

The quality of the balloons is very similar, although Qualatex have been around for longer, and so currently have a better name. Sempertex balloons claim to be made of a thicker layer of rubber, and therefore stronger.

The main differences with the two makes are that the Sempertex 360 modelling balloons are claimed to be an extra 10" longer than the Qualatex equivilant. They also make heart balloons with a longer stem, allowing them to be tied to other balloons more easily.