Petitcoats are like slip worn under a saree. Traditionally they were needed to tuck the saree and hold the saree in place.
With a One Minute Saree, a petitcoat is not needed but a matter of preference. In every saree on our website, you will see an option "in-built petitcoat" - this is basically an inner lining and it is recommended for lighter sarees or to give a fuller form. Some people opt to wear a slip or leggings and for heavier materials it may not be required.