When using the Standard 1:4 Heavy Duty chain drive the continuous chain must be fitted with a chain tensioner (CHSAFE-R) screwed to the wall no lower than 150cm from the floor.
State the exact length you would like the chain making to in the box provided.
To calculate maximum allowable chain length to comply with new safety regulations:
Max drop of chain = (Height of headrail from floor in cm - 150cm)
Length of chain = drop x 2