Specifications include, but are not limited to: a. Filters changed on a 60 day basis must be changed on the scheduled due date plus or minus one week, or the service will be considered late. Due dates must be set at two months after the last filter installation. b. Filters changed on a monthly basis must be changed on the scheduled due date plus or minus three days, or the service will be considered late. Due dates will be set at one month after the last filter installation. c. Filters changed on a yearly basis must be changed on the scheduled due date plus or minus one (1) week, or the service will be considered late. Due dates will be set at two (2) months after the last filter installation. d. Filters changed on a quarterly basis must be changed on the scheduled due date plus or minus one (1) week, or the service will be considered late. Due dates must be set at two (2) months after the last filter installation. e. Filters changed every two (2) weeks must be changed on the scheduled due date plus or minus one (1) day, or the service will be considered late. Due dates must be set at two (2) weeks after the last filter installation