What's the Red plastic cap in the brass valve on a GAS IT Plus bottle?

Within the GAS IT Plus bottle valve set you will see a red plastic cap that's stuck in a brass valve.

This cap is not designed to be removed and the PRV is not designed to be played with or adjusted. Removal of the red cap will invalidate the bottles warranty.

This red plastic cap is a tight fitting dust cap in the pressure relief valve ( PRV ) and the red cap is designed to protect the valve from dirt and dust and is not to be removed from the pressure relief valve as the warranty will be voided if it is removed due to the part holding the safety red cap in place will become broken. 

Removing it will not affect the safety or working of the valve but you do risk it coming out and dirt getting in to the valve.

No extra pipes or fittings are needed to be screwed into the PRV.

All gas bottles, like exchange bottles, and all our gas tanks have a PRV of some sort as it controls the safe release of gas pressure in the event of a fire.