Trenches give soldiers cover against enemy fire and allow movement from one part of the line to the other. This kit provides trench pieces of various lengths plus corner pieces. Each section of trench only provides one side of the trench (as many rules sets call for) but by placing two sections back-to-back you can have a complete trench. The 15mm kit includes six 8" trench sections, eight 4" trench sections and eight corner pieces. The 10-12mm kit includes nine 6" trench sections, six 3" sections and twelve corner pieces. The 20mm kit includes six 12" trench sections, eight 6" sections and eight corner pieces. The 28mm kit includes four 12" trench sections, eight 7 1/2" trench sections and eight corner pieces.