In this paper we illustrate the design of rubber Soller slit collimators suitable for work in neutron spectrometry, at present in use at our Laboratory. Experimental tests performed on the collimators proved the rubber lamellae to be very effective as collimating material. The performance of these collimators is that to be expected on the basis of the ``Gaussian approximation'' applied to the attenuation of a neutron beam proceeding through the typical elements of a crystal spectrometer. The simplicity of construction and the performance of these collimators lead us to recommend their use in the field of neutron spectrometry.