It is recommended to use magnetic tapes with a thickness of 1.2 mm or more, as shown on this page. If the tape is thinner than this, the magnetic force may be insufficient. If the magnetic force is still not enough even with tape over 1.2 mm thick, you can strengthen it by overlapping about three sheets of tape.
In general, the side without adhesive has stronger magnetic force. I often use two pieces for optimal results.
Please refer to the website link for detailed features and pricing information.

Product Data
1)
Website: Product Page
Brand: DAISO
Name: Magnetic Tape
Product Number: 4549131587487
Size: W – 10 mm, L – 3 m, T – 1.2 mm
Material: Rubber Magnet
Feature: Single-Sided Adhesive Type

2)
Website: No Online Store
Brand: SERIA
Name: Strong Anisotropic Magnetic Tape
Product Number: 649-MGT
Size: W – 20 mm, L – 1 m, T – 1.2 mm
Material: Magnetic Sheet
Feature: Single-Sided Adhesive Type

3)
Website: No Online Store
Brand: SERIA
Name: Single-Sided Adhesive Magnetic Tape
Product Number: 32-729
Size: W – 20 mm, L – 1.5 m, T – 1.2 mm
Material: Rubber Magnet
Feature: Single-Sided Adhesive Type