These LED panels can add “hot swap” capability: pull out depleted panels and quickly exhchange for fully charged ones. You may also need more to replace lost/damaged LED panels. These are compatible with VPR 400 series. To fully equip a single VPR, you will need to order two (2) panels. One charge will provide 1-3 hours of light, depending on your dimmer settings. Adapters are included to mount the LED panel on the hotshoe of your video camera, SLR or tripod.