These macromolecules are polar [polar: having different ends] because they are formed by head to tail condensation of polar monomers. Let's look at the three major classes of macromolecules to see how this works, and let's begin with carbohydrates.
Bostwick Steel Lath Company advertisement for steel truss loop type metal lath in 1920. A lath or slat is a thin, narrow strip of straight-grained wood used under roof shingles or tiles, on lath and plaster walls and ceilings to hold plaster, and in lattice and trellis work.
The Metal Bar is a crafting material in Unturned. It is used to make one of the strongest barricades and doors such as Bars Fortification and Vault Door. It can be found at Construction Locations, dropped by Construction Zombies or crafted from Scrap Metal. 1 Scrap Metal + Blowtorch = 2 Metal Bars.