The BDX 2000 Insulation & underfelt collars reduces heat loss by providing additional insulation around the window frame. The underfelt collar which is included this package or can be bought seperately as the BFX 1000 minimises the risk of condensation and includes a transverse drainage gutter that leads water away from the head of the window if a tile or slate is broken above the window.
The LSG 1000 is used as a mounting base for the internal lining around the roof window on the inside of the ceiling, it also includes the BBX 0000 vapour barrier or you can buy the BBX on it's own.
The BBX 0000 Vapour barrier provides a vapour and air tight install and prevents condensation from forming in the roof constructions.
The VELUX fixing frame is for the CFP/CVP flat roof windows. It's a steel crafted frame that aids installation and enables a clean finish around the kerb.
All these accessories are optional but will either ease installation or improve your window performance or both.