If you want a 4" outer checkerboard border, you can also go with a checkerboard of four 1" squares across. This is another number that will divide evenly into 9 and 2. You would cut your strips 1 1/2". The problem with tearing is that it may distort the fabric up to 1/2" from the tear line. With such narrow strips, this may not work. Be sure and do a test tear before proceeding with all the fabric. You may have to punt & go with rotary cut strips.