Businesses in the electronic cigarettes and vapour category, often called vape shops, sell devices that heat liquid to produce an inhalable aerosol. Products may include refillable pod systems, vape pens and more advanced kits, along with e-liquids in different flavours and nicotine strengths. Shops may also stock replacement pods, tanks, coils, mouthpieces, batteries and charging equipment. In the UK, regulated e-cigarette products containing nicotine must meet applicable product and notification requirements, including notification to the Medicines and Healthcare products Regulatory Agency. Staff may explain the differences between device types, how to fill and operate a product, and how to replace coils or other parts. Some retailers offer basic troubleshooting, device setup and battery-safety guidance, while others provide a narrower range of products or sell them online.