Everything else on this page is bag silage — fodder packed into an individual sealed bag. A bunker or pit silo works differently: fodder is packed into a fixed trench or bunker structure and then sealed under a single large sheet, with the weight of the fodder itself (plus weights placed on top) pressing out the air to create the anaerobic environment. This cover is that sealing sheet.
Because bunker size varies enormously from farm to farm, this is priced and supplied per square metre rather than as a fixed bag size — you tell us your bunker's dimensions and we cut and supply coverage to match, generally with enough overlap at the edges to weight down and seal properly. This is typically the right choice for farms and cooperatives storing larger total fodder volumes than individual bags can practically hold, where a fixed bunker structure is already in place or being built.