We present B2B-Swipe, a single-finger swipe gesture for a rectangular smartwatch that starts at a bezel and ends at a bezel to enrich input vocabulary. There are 16 possible B2B-Swipes because a rectangular smartwatch has four bezels. Moreover, B2B-Swipe can be implemented with a single-touch screen with no additional hardware. Our study shows that B2B-Swipe can co-exist with Bezel Swipe and Flick, with an error rate of 3.7% under the sighted condition and 8.0% under the eyes-free condition. Furthermore, B2B-Swipe is potentially accurate (i.e., the error rates were 0% and 0.6% under the sighted and eyes-free conditions) if the system uses only B2B-Swipes for touch gestures.