Sturdy, press-formed KRD access door for rectangular ducts or flat surfaces made of PVC, PE, PP or PPs. The KRD access door is made of an outer cover plate made of PVC and an inner cover plate made of PVC, PE, PP or PPs depending on the material of the duct. Both cover plates are pulled together thanks to two bolts and knobs. In doing so the duct wall is clamped evenly between the two access-door covers. The self-adhesive EPDM foam gasket makes the access door air-tight even by higher pressures. The oval shape of the access door allows an easy installation into the opening.