In practice, the thickness required to produce true-zero order waveplate is about tens of micron according to the wavelength, which is too thin to manufacture. For this reason, multiple order waveplate often provides a convenient means of producing the required retardation. Dream Lasers provides two kinds of multiple orders waveplates---low-order and multi-order which are classified by the thickness. The retardation value of a multiple order waveplate is strongly dependent on temperature, wavelength, angle of incidence and degree of collimation. Zero-order waveplates do not have this dependency. A zero-order waveplate is constructed of two multiple order waveplates (optically contacted, cemented or airspaced) with their axes crossed. Thus, the effect of the first plate is canceled by the second, except for the residual difference between them. The following Table based on 532 nm, λ/4 waveplates with retardation tolerance <λ/100 gives you a rough idea of the comparison among all the orders waveplates.