Bolt VM-1010 TTL Macro Flash Compatible with VM-1020 Transceiver, Ideal for Use with Additional Heads, Measures 2.8 x 3 x 2.4", Guide Number: 33 @ 328', Recycling: 4 sec at Full Power, 4 Channels / 3 Groups, 5500K, CRI90, Multiple Heads Make Ring Light...