[ Fits 29-1/2~42-1/8" Doorway Width]. [Fits 42-1/8"-72-4/5"Doorway Width]. US Barn Door Hardware. UK Barn Door Hardware. Adapt to door thickness: 1-1/5" to 1-3/4",less than 21" Wide.4FT Sliding Door Hardware Kit fits maximum SINGLE Door leaf width:21".