"Not sure!"
The info with the strips states not to be used above 350F (Gas 4) so no good for sponges. Baked my usual Christmas cakes using them but they were dried out long before the cake was cooked so maybe best on smaller cakes (mine are a 9" square and a 2lb long loaf tin). Not sure of the 'no cracks' or 'crusty edges' either , my cakes had both. Probably works as good as the old wrapping newspaper round tins but not as fiddly although not a magic invention!
support_agent A note from the team
I'm sorry that the product didn't live up to your expectations - we'll be in touch shortly.