60 window frame PC60K 0.97kg/m60 middle style PC60ST 1.05kg/m60 open-in leaf PC60NS 1.042kg/m60 open-out leaf PC60WS 1.142kg/m60 glass holdfast 1 PC60DY 0.29kg/m60 glass holdfast 2 PC60SY 0.19kg/m60 screen leaf PC60SS 0.45kg/m