tell me a starting paragraph for the heading " difference between working hours in different countries"​

This device blocks an opening along the base/floor of stairs or other walking or working surfaces where materials or body parts might otherwise inadvertently fall through. it should be 4 inches high, with not more than ¼ inch clearance above the floor

Which inference can a reader make based on the information in the excerpt?

Which secondary effect of advertisement happens when a customer is satisfied by a product and buys it for a second time?