From Blindspares - Good Quality Vertical Blinds Bottom Chain in WHITE plastic, 3.5" (89mm) wide, pack size - 50 clips (enough for 25 slats/6ft wide blind). Our 3.5" plastic bottom chain has 11 balls between each clip, our 5" plastic bottom chain has 15 balls between each clip, dont worry if your old chain has a different number of balls, they are for weight/design purposes only and do not affect the length of the chains themselves. Vertical blind fabrics are available in 2 standard sizes 3.5" or 5", and the chains are designed to fit these 2 sizes, so for 3.5" fabric you need the 3.5" chain , for 5" you need the 5" chain How much chain do I need? You will need twice as many clips as you have fabric slats, so if you have 24 slats, you will need 48 clips of chain, so you would need to buy a pack of 50 clips