An optical tube assembly having at least one optical waveguide, at least one dry insert, and a tube. In one embodiment, the dry insert has a first layer and a second layer attached together with an adhesive. The dry insert also includes a plurality of particles having an average particle size of about 600 microns or less for inhibiting microbending. The first layer may be a polyurethane foam having an average cell size of about 1000 microns or less and the second layer is a water-swellable layer. The dry insert is disposed within the tube and generally surrounds the at least one optical waveguide and the tube assembly can be a portion of a fiber optic cable.