Pentax AF540GZ II flash New Weather Resistant Flash Unit for Pentax SLR's with Case (Black) Weather resistant All Weather (AW) construction pairs perfectly with PENTAX WR DSLR cameras. High Guide number for increased range and versatile flash performance P-TTL mode with pre-flash allows for more accurate strobe photography Constant light source for video or long exposure still photography. High speed on camera and high speed wireless flash is available in P-TTL modes Flash exposure compensation through a simple control dial. LCD display shows the effective range of the flash