The most common way to simplify extensive Monte-Carlo simulations of air showers is the thinning approximation. We study its effect on the physical parameters reconstructed from simulated showers. To this end, we created a library of showers simulated without thinning with energies from $10^{17}$~eV to $10^{18}$~eV, different zenith angles and primaries. This library is publicly available. Various physically interesting applications of the showers simulated without thinning are discussed. Observables reconstructed from these showers are compared to those obtained with the thinning approximation. The amount of artificial fluctuations introduced by thinning is estimated. A simple method, multisampling, is suggested which results incontrollable suppression of artificial fluctuation and simultaneously conserves computational resources as compared to the usual thinning.

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 4 (HE part 1), pages 641-644