Amazon has the Oregon Universal Chainsaw Field Sharpening Kit (617067) for $11 with free shipping on $35+ or with Prime. This kit includes 1" x 5/32" round saw chain file, 1" x 3/16" round saw chain file, 1 x 7/32" round saw chain file, 1 x 6" flat file, 1 x file guide, and 1 x universal file handle.