This is the skirt at the bottom of the PAL liquid booster. It is designed to replace the inaccurate parts in the Heller 1:125 Ariane 4 kit. The part contains 4 skirts.
The scale listed as 1:128 is in fact 1:125, for the Heller Ariane 4 kit.
For more information, see http://acme-engineering.nl/esa.html