The plate-covered belt popularly called a cingulum was more likely known as a balteus. In the mid-first Century CE a single belt to support dagger and apron was most common, but the two crossed belts worn in Augustan times still appeared.
Beltplates are generally described as either narrow or wide. The narrow plates are the older style, the narrow belts often being worn in pairs. They are usualy cast brass and frequently tinned or silvered, and inlaid with niello. They range in width from 1" to 1 1/2", and in length from 2" to 2 1/4". Wide plates, measuring 1 1/2" to 2" wide by 1 3/3" to 2 1/2" long, are generally stamped from a thin brass sheet, and are also often tinned or silvered. Frequently the ends are rolled, sometimes with ball-headed pins inserted in the resulting tubes.
The buckle and dagger frogs (or "suspension discs") are cast brass, with hinge tubes. Matching hinge tubes are either cast directly with the appropriate belt plate, cut into a rolled plate, or made separately (cast or folded) and riveted behind a plate.
The plates are riveted to a leather belt no wider than the plates themselves. Some cast plates have integral pegs on the back to serve as rivets. Round or square washers may be used. The leather is 3-6 ounces and may be left plain, or dyed red, black, or another color. (In any case it should be well-oiled and greased.) The buckle is most often seen on the right end of the belt, while the free end is narrowed to fit it. Be sure to position the dagger frogs far enough apart to accept your pugio scabbard. The Velsen belt and at least one sculpture imply that some belts had no plates at the back.
The apron, also called a sporran or groin-guard, was a decorative item derived from split belt ends. It has from four to eight leather strips 3/4" to 1" wide by approximately 10" long. Wide belts characteristically have four of the wider strips while a larger number of narrow strips are usually seen only on narrow belts. each strip ends in a dangling terminal, and has up to 16 disc-shaped studs. Usually these are cast (and occasionally inlaid) with a peg on the back to serve as a rivet. Studs can also be cut from sheet brass and secured with a rivet through the center. The studs can be placed to form horizontal rows, or staggered (although the terminals all hang at the same height), or even spaced up to 2" apart.
The apron commonly hangs over the top of the belt (being riveted to the back), but can hang down from the bottom edge, especially on narrow belts. In such a case the top of each strip may have a small plate like a miniature belt plate.
All apron fittings may be tinned or silvered to match the belt. The leather may be dyed like the belt. There may be a reinforcing stitching of linen thread down each side of a strip, or a decorative tooled line.
It is clear that the balteus was a valuable personal possession. Although made in Army workshops and probably a required item of equipment, it was perhaps not issued at random but more carefully chosen by the soldier according to his own tastes and budget.