706 – Box Plastic, ABS Black Cover Included 4. 67mm) from Keystone Electronics. The NTPK distribution box (corner design) is designed for efficient air flow distribution in mechanical ventilation systems. Both versions have a single housing with 6 branches of 75 mm diameter. Do you have a question or a project enquiry that you'd like to talk to us about?Order today, ships today. Himel supplies affordable electrical offers that create value for. Distributors - Distribution box.