A closed-loop seal having an irregularly shaped profile to seal a pivot assembly of a track assembly comprises a body comprising an inner diameter wall, an outer diameter wall, a first sidewall, and a second sidewall, wherein at least one pairing of the inner and outer walls and the first and second sidewalls are non-parallel. The irregularly shaped profile can comprise a curved rectangular profile or a trapezoidal profile. Walls of the body can be joined at curved surfaces having uniform or different radii of curvature. The seal can comprise urethane.