Available in 2 scales: the scale marked 1:128 is made for the Heller 1:125 Ariane 4 kit. 1:144 is for the Revell Ariane 4 kit.
this part contains the attachment fittings for 2 boosters:
4x pins with springs, and 1x plate for each booster.
You also need the boosters themselves. Longer boosters for Ariane 4: https://www.shapeways.com/product/62LGHPWYA/ariane-4-pap-booster
Shorter PAP booster for Ariane 3: https://www.shapeways.com/product/TWA5M8MJK/ariane-3-pap-7-35-boosters
For more information, see http://acme-engineering.nl/esa.html