Looking for the best car diffuser that is electricity-free? Try this aromatherapy essential oil diffuser by RoyAroma. This oil diffuser brings pleasant smells to your car using felt pads (different from the electric options of related products). You get two diffuser lockets that house the felt pads which you drip essential oils on. The felt pad size is 22mm, and the oil diffuser stainless steel lockets themselves are 30mm.\r\n\r\nWhy We Like It - RoyAroma Aromatherapy Essential Stainless Freshener\r\nThe RoyAroma Aromatherapy Essential Stainless Freshener is an affordable option if you\u2019re looking for an essential oil diffuser that doesn\u2019t need electricity to work. It utilizes a felt pad in each car diffuser to spread a pleasant aroma around in your car air.\r\n\r\nPerformance\r\nYou can use these aromatherapy essential oil diffuser stainless steel lockets in your home, kitchen, or car (the YJY Car None Sponge Wick Aromatherapy Intermittent can also be used in your car). The diffuser stainless steel locket design is 30mm, so you can put it basically anywhere because it doesn't require any electricity to function properly. Each package comes with 12 replacement felt pieces so you won't have to mix and match essential oils on the pads (which could result in a less than pleasant experience!). Each locket has small round holes on the back to increase the diffusion potential.\r\nDesign\r\nSince these diffusers are not electronic (try the InnoGear Essential Refresher Ultrasonic Therapy for an electronic alternative), they have a very simple design. The 30mm lockets (with either a "tree of life" or a "sunflower" design on the front) house the 22mm felt pads that are used to absorb the essential oils. They can then be mounted on a car vent, or set in a place of your choosing. The lockets have holes on the back to increase diffusion power, and a powerful magnetic closing system to ensure that the pads don't come out.\r\nValue\r\nBased on the available product information, customer feedback, and overall design, we would say this product has a pretty good value (the Gulaki Diffuser Essential Oils Multifunction is an electronic alternative that also has good customer reviews). For only $10.99 you get two diffuser lockets and 12 replacement felt pads, so you can go a while before having to replace the pads. RoyAroma offers free shipping and returns on this product as well, although this product does lack a warranty.\r\nRoyAroma Aromatherapy Essential Stainless Freshener Wrap Up\r\nThe RoyAroma Car Aromatherapy Essential Oil steel locket air freshener is your best choice if you want an electricity-free car diffuser. It comes with two stainless steel decorative lockets, 12 replacement pads, and includes free delivery, so it is well worth the $10.99 price tag. We wish that it came with essential oils as well, but for the price that is not a serious concern.