Features:
The YONGNUO speedlite YN-E3-RT II is a for wireless flash . It can control to 5 groups(15 units) of speedlites that have a multiple flash function using ratio transmission.
Flash Modes: ETTL/M/Multi/GR4/ flash modes. supports 1st curtain, 2nd curtain(Only in M mode), high sync.
New designed dial and display interface for easier operation, supports to set the focal length(ZOOM) of the slave flash.
Firmware can be updated via USB( USB), Built-in assist beam emitter, transmission is 100m.
Two-way 2.4G communication, fully compatible for ST-E3-RT/600EX-RT/YN-E3-RT/YN968EX-RT/YN600EX-RT(II)/YN686EX-RT/YNE3-RX.

Specifications:
Type: On- Speedlite
Exposure Control Syestem: E-TTL II/E-TTL Autoflash, Manual Flash, Stoboscopic Flash, Flash
Frequency: 2405-2475MHZ
Modulation System: Primary Modulation: OQPSK, Secondary Modulation: -SS
Channel: Auto, . 1-15
ID: 0000-9999
Slave Unit Control: to 5 Groups(A/B/C/D/E), to 15 Units
Transmission Distance: Approx. 100m
Flash Ratio Control: 1:8-1:1-8:1, 1/2-Stop Increments Flash Exposure
FEB: ±3 Stops in 1/3-Increments(When used with flash exposure compensation)
Manual Flash: 1/1-1/128 (1/3-stop increments)
Stroboscopic Flash: Provided(1-500Hz)
Flash Exposure Confirmation: Flash Exposure Confirmation
Model Flash: Fired with ' Depth-of-field preview button.
Linked : Provided
Custom Functions: 9
Assist Beam Emitter: Provided
Firmware Update: Provided
Source: 2 AA/LR6 Alkaline Ni-MH (Not Included)
Flash : Approx. : 10 Continuous Hours
Saving: off After 5 min, of idle Operation
Package Size: 11 * 9 * 7.5cm / 4.3 * 3.5 * 3.0in
Package Weight: 240g / 8.5oz

Packing List:
1 * Speedlite
2 * Shutter Cable(LS-/C1 & LS-/C3)
1 * Storage Bag
1 * User Manual(English & Chinese)