KLKRsmall duct incl. cover with turning bolts KLKsmall duct incl. cover BKTE 110floor duct telescope insert, height=110 mm BKTE 100floor duct telescope insert, height=100 mm BKOS 110not perforated, height=110 mm BKOS 100not perforated, height=100 mm BK 100perforated, height=100 mm