An aspis was deeply dished and made primarily of wood. Some had a thin sheet of bronze on the outer face, often just around the rim. The convention was to decorate the shield.
The aspis measured at least 0.9 metres (2 ft 11 in) in diameter and weighed about 7.3 kilograms (16 lb), and it was about 25–38 millimetres (0.98–1.50 in) thick. This large shield was made possible partly by its shape, which allowed it to be supported comfortably on the shoulder. The revolutionary part of the shield was, in fact, the grip. Known as an Argive grip, it placed the handle at the edge of the shield and was supported by a leather or bronze fastening for the forearm at the center, known as the porpax. This allowed hoplites more mobility with the shield, as well as the ability to capitalize on their offensive capabilities and better support the phalanx. The shield rested on a man's shoulders, stretching down to the knees. It was theorized they were designed for a mass of hoplites to push forward into the opposing army, a move called othismos, and it was their most essential equipment, though this is now an outdated theory.  That the shield was convex made it possible for warriors to use it as a flotation device for crossing rivers.
Such shields did not tend to survive the passage of time very well, and only one aspis has survived into modernity with sufficient preservation to allow us to determine the details of its construction: this shield is called the "Bomarzo" or "Vatican" shield, and it is currently located in the Vatican, within the Museo Gregoriano Etrusco. It was discovered in 1830 near Bomarzo in Lazio, central Italy.