Keener Rubber manufactures rubber bands in a wide variety of different sizes.  We typically produce bands that range from 7/8' to 11-1/2" in flat length with a wall thickness of .035, .045, .050, .062, .080 and .125.  We can provide a cut width of 1/32" to over 6".  Please contact us if you can't find what you are looking for, we can provide bands in the full spectrum above if you are willing to commit to a reasonable minimum quantity.