DSE201 RCBO's, DS203NC RCBO's and DDA200 RCD blocks. Where DSE201 RCBO's are utilised all MCB's and RCBO's are bottom fed. For DDA blocks all components are top fed and should not be mixed with DSE201 RCBO's. ECM chassis are available as universal (dual feed), top feed or bottom feed according to installation requirements. Top / bottom feed chassis are supplied with a loose phase identification label that can be applied to the chassis according to the installation requirements.