The Bestway product associated with the number 60309 is the Lay-Z-Spa Floor Protector, which is a ground mat system rather than a pool cover. Based on its specifications, it does not have a traditional closure type but instead uses an interlocking (attachable) design to stay together.
Product Description: Bestway 60309 Lay-Z-Spa Floor Protector
This floor protector is designed to provide an extra layer of insulation and protection for your inflatable hot tub and the ground surface beneath it.
Closure/Connection Type: Interlocking pieces. The package contains 10 pieces (9 attachable tiles and 1 individual mat for the spa heater) that snap together like a puzzle to form a square base.
Dimensions: The assembled protector measures approximately 2.16 m x 2.16 m (85" x 85").
Material: Made from durable, high-density polyethylene (PE).
Purpose:
Protects the spa liner from abrasive debris on the ground.
Adds thermal insulation to help maintain water temperature.
Compatibility: Suitable for all Bestway Lay-Z-Spa sizes.