The UMP-45 is a compact submachine gun with a predominantly polymer construction, featuring a matte black finish for a tactical appearance. It has a distinctive angular design with a folding stock, textured grip for enhanced handling, and a short barrel with a flash hider. The weapon includes detailed iron sights, a Picatinny rail on top for optic attachments, and a magazine well that accommodates a curved .45 ACP magazine. Surface details include subtle manufacturer engravings, wear marks around high-contact areas, and a slightly roughened texture on the grip and stock for realism.