Highland Mug The Highland Mug is a mug with a capacity of 350ml. The mug is double-walled and made of stainless steel. The mug has a plastic rim, handle and lid. In the lid of the mug is a drinking opening. Because the mug has a double wall this will retain the heat longer. The mug is available in three colors. The Highland Mug can be printed with your own design or logo. You can print your design or logo in up to 4 colors. You can also engrave your design or logo. The Highland Mug is BPA Free.