Could You Provide More Details about the Specific Rechargeable Battery for the Mindful Audio?

Please use a button-top, rechargeable, 18.63mm x 67.18mm(approximate dimensions) 18650 battery. There are 2 types of 18650 Lithium-ion batteries, the button top (68mm length) and the flat top (65mm length) batteries and they come with different capacities. Mindful Audio takes the button top type. You can also refer to the link.