Canon Infared speedlite trigger, ST-E2, Shoe Mount for many Canon speedlites

Description

Slightly used. As Is. Works fine.
With the Speedlite 550EX and the Speedlite Transmitter ST-E2, it is now possible to use multiple Speedlites under full E-TTL control and without the need for any interconnecting wires. Developed in conjunction with the Speedlite 550EX and the EOS-3 camera, this master control device for a wireless Speedlite flash system meets professional and advanced amateur standards. Its dedicated transmitter controls up to 3 Canon 550EX Speedlites as slave units 33 feet away outdoors and 49.5 feet away indoors. It is mounted as a clip-on with a shoe lock lever and locking pin.
Compatibility with a variety of Canon flashes.
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Canon ST-E2 Features
Advanced Features:
E-TTL Compatible Since it is compatible with E-TTL auto flash functions, groups of 550EX Speedlites are able to take advantage of High-Speed Sync, FE Lock, Flash Exposure Bracketing, and Pre-flash evaluative metering.
Built-in AF-Assist Beam:
The AF-Assist Beam automatically fires in low-light and low-contrast situations to assist the camera's auto focusing system.
Sets and Controls Flash Ratios:
Transmitter ST-E2 sets and controls all functions of its Speedlite 550EX slave units. Flash ratios,for example,are controllable between 2 Speedlite 550EX groups.
High Speed FP Flash:
High Speed FP (Focal Plane) flash for synchronization at all shutter speeds is available, even the EOS-3s top speed of 1/8000. Larger apertures can be used to obtain better background blur. And fill flash can be used for moving subjects in daylight. Weight:3.5 oz./100 g (Including battery).