Infinuvo Virtual Blocker for Hovo 510 and Compatible Robotic Vacuums Infinuvo virtual blocker for Hovo 510 series and bObi classic robot vacuum cleaner. Create an invisible barrier that the vacuum will not across, so you can confine the vacuum in certain cleaning area Make sure to complete the paring of new virtual blocker with your Hovo 510 before using it. Requires 2 AA batteries (not included) WORRY-FREE GUARANTEE! We are US based company. In case you are not completely satisfied with the product, just return it within 30 days for a full refund. This battery carries 1 year limited warranty by Metapo.