K15 Phenolic Rainscreen Cladding Boards This insulated rainscreen board with composite foil on both sides and is used to insulate behind cladding systems, and should be installed between proprietary fixing rails.
K – is this your tax ? If so your personal allowances are exceeded by deductions such as employment benefits or state pension so a notional amount of extra income is taxed to avoid you being underpaid at the end of the tax year.