The AC5 RF Soft Shield is a simple solution to reduce interference & improve performance of the Flex TT5 Transceiver. Special RF fabric & a shoe filter shields the Flex TT5 Transceiver from RF noise emitted by some Canon Speedlites (580EX II, 580EX & 430EX). The Canon 550EX, 270EX & newer 430EX II emit relatively low EMI & work well with the Flex TT5 without shielding. The AC5 allows easy access to all flash controls as well as a full range of flash positions. The AC5 can either be stored on the flash or it can be removed & rolled up making it easily storable in your camera bag. Its portability makes it an attractive RF noise solution. The AC5 RF Soft Shield can be used when using a high-power external battery. The AC5 is for use with receiving flashes only & is not for use with your on-camera flash. NOTE: The AC5 is not designed for horizontal use on a boom mount or light pole; for these situations please see the AC7 RF Hard Shield. The AC7 is also the perfect solution for use with an umbrella with its centered umbrella mount.