What is the application for 'modular sizes' (eg 390 x 100 x 190 - even 390 x 90 x 190)?
Is a new standard being introduced? Most block manufacturers websites show this size in addition to the metric ones.
Also, especially, why 90mm? Anything less than 100mm in a wall leaf is usually frowned on.
I inadvertently bought some grr...grrr...
TIA for any info