A dry flowable additive for aqueous urea-based fertilizers made of solid urea formaldehyde polymer, N- thiophosphoric triamide, and, optionally, dicyandiamide, wherein the liquid fertilizer containing the additive provides reduced nitrogen loss from the soil. The brace comprises an upper bracket assembly, a lower bracket assembly, and certain torsional spring assemblies. The generated digital edge and the delay encode the time and energy of the analog signal using pulse width modulation. The sensing unit locates at one side of the panel and the sensing unit senses a plurality of first light signals reflected by an object and senses a plurality second light signals of an ambient light. The spark arrester is a screen held within the exhaust muffler and removably coupled to the exhaust pipe. The optical performance monitor receives and detects relative power levels of each representative portion of the equalized component wavelength signals.