These are clearly bigger than a normal brick, but i couldn't tell how big from the article. This has a diagram of one: https://www.rspb.org.uk/our-work/rspb-ne

These are clearly bigger than a normal brick, but i couldn't tell how big from the article. This has a diagram of one: https://www.rspb.org.uk/our-work/rspb-news/news/stories/new-homes-for-swifts--the-manthorpe-swift-brick/ https://www.rspb.org.uk/our-work/rspb-news/news/stories/new-...