The chemical heat warmers bags are meant to be used with a camera parka, classic or pro. Although the camera parka blocks wind, humidity and protects from cold, you may want to add heating sources inside the camera parka. Ideal when shooting in extreme cold, spending long hours outside or timelapse photography to increase battery life.
The bags come with Velcro to secure them inside the parka. You can place the Velcro where you want for efficient use of the chemical heat packs.
The chemical heat warmers bags come in a set of 2, with stick on Velcro for the camera parka.