HOW TO ORDER A guide on how to order Breather Plug & Drain Plugs from CMP: e.g. 781 – D – M – 3 = Ex d – M25 e.g. 781 – E – M – 3 = Ex e – M25 Other Thread Variations are available on request. For further information on ordering please refer to how to order. The CMP 781E range of Increased Safety type ‘e’ breather plug / drain plugs have been tested together with CMP serrated washers to ensure that in areas that are subject to vibration, the breather plug / drain plugs do not suffer from self-loosening and in advertently fall out of the enclosure. Serrated washers are not included as standard but can be ordered separately.