From Fender:

The all-new Rumble Series is a mighty leap forward in the evolution of portable bass amps.

Rumble Series speaker cabinets have been re-voiced to produce a superior level of sonic detail and low-frequency translation. And for even greater performance and convenience, all Rumble cabinets are equipped with Fender’s patented Magnetic Rumble Head-Attachment System. Additional upgrades include Eminence drivers and premium HF compression tweeters.

• Rated at 700 watts (program), 350 watts (continuous)
• Two 10″ Eminence speakers
• Compression driver horn with attenuator switch
• Magnetic Rumble amp head attachment system
• Lightweight ported plywood enclosure with removable grille
• A great companion to the 500 combo