Here are some common items used by professional window cleaners to ensure crystal clear windows:

1. Squeegee: This is a critical tool that is used to remove water and cleaning solution from the glass. They come in different sizes and shapes, depending on the size of the window.

2. Microfiber Cloth: This is a soft and absorbent cloth made of tiny fibers that help to clean and polish the glass surface.

3. Bucket: A bucket is used to hold water, cleaning solution, and other necessary equipment. Professional cleaners use a bucket with a sieve to ensure the squeegee doesn't pick up dirt particles while cleaning.

4. Scrubber: A scrubber usually has a Velcro or clip-on attachment for a squeegee and helps loosen dirt from the glass. The scrubber can be made of synthetic fabric, microfiber, or natural fibers.

5. Cleaning Solution: Professional window cleaners use specific solutions that are designed to clean windows without leaving any residue. The cleaning solution can be made of natural or synthetic ingredients, depending on the needs of the client.

6. Ladder: A ladder is essential for washing windows that are high off the ground and can't be reached from inside the house. Professional cleaners use sturdy ladders that can support their weight.

7. Extension Pole: An extension pole can be attached to the scrubber or squeegee, making it possible to clean windows that are hard to reach without the use of a ladder.

8. Safety Equipment: Professional cleaners always wear gloves, goggles, and shoes with slip-resistant soles to protect themselves from any accidents.

Using these tools, professional window cleaning services can ensure that your windows remain spotless, letting in the sunshine and improving the aesthetics of your home or business.