Cat flap help

[FedUpofLockdown123]

I usually leave a window open so my cats can get in and out but looking at getting a cat flap instead to stop the paw prints and it's starting to get cold.

I don't have much money at the moment so was looking at this until I can afford something better. Can anyone tell me if this will be any good or do I need to purchase a tunnel extender whatever that is . It will be being installed into a wooden front door.

www.amazon.co.uk/dp/B00B17ETR6/ref=cm_sw_r_cp_apa_i_El6pFbG86CDZ9?tag=mumsnetforu03-21

I think you will need a tunnel otherwise the inside of the door will be exposed which could be rough on your cats belly and it could also get damp in the wood if a bit of rain gets in through the flap

I'm sure that will be absolutely fine for a wooden door. The tunnel extenders are for putting a flap in a wall rather than a door!