Timely projections of product sales for a reporting time period are obtained by combining actual sales data received from reporting stores and estimated sales data for non-reporting stores. An embodiment of the invention includes a minimum of three channels for digital computation in Primary Flight Computers and four channels for digitalanalog conversion in Actuation Control Electronics. The male clip is loosely inserted through the insertion hole and engaged with the female clip around the insertion hole via an abutting brim, thereby producing a gap between the insertion hole and the male clip, thus increasing the degree of freedom of positional adjustment, reducing the steps for mounting and controlling the accuracy of the attachment, reducing the overall cost.