This is a popular choice among fighters for a few reasons. These are usually easier to craft and thus cheaper to buy, and unlike other options, they offer horizontal flexibility rather than vertical. A fighter is thus more able to make side-to-side movements with less restriction.
The 5-piece breastplate often has no back-plate though, but kidney plates instead which wrap around the sides and toward the back, not covering the back. So fighters, watch your backs.
The 5-piece also has no faulds. It’s bottom edge is not from a single piece of plate since the plates are vertical and arranged horizontally. This means you get a bottom edge made up of overlapping plates, to which faulds would hardly attach well.
Tassets can be worn with a 5-piece breastplate, but often this is not the case. Usually the fighter wearing a 5-piece breastplate enjoys the higher mobility/agility from not having faulds and tassets hanging down. Less protection, but lighter weight.
More soon…