The 45mm Black/Black Nike Sport Band is a specific model of Apple Watch band designed in collaboration with Nike. Here are some details about this particular band:

1. Compatibility: The 45mm Black/Black Nike Sport Band is designed to fit the larger Apple Watch models, specifically the 45mm version. It is compatible with Apple Watch Series 4, Series 5, Series 6, and Apple Watch SE.

2. Design: The band features a sleek, sporty design with a black color scheme. It is made of a durable fluoroelastomer material that is sweat-resistant and comfortable to wear during physical activities.

3. Size and Fit: The band is designed to fit wrists ranging from approximately 140mm to 220mm in circumference. It has a pin-and-tuck closure system that allows for a secure and adjustable fit.

4. Nike Branding: As part of the Nike collaboration, the band prominently features the Nike logo and branding elements. It adds a sporty and distinctive look to the Apple Watch.

5. Interchangeability: Apple Watch bands are designed to be easily interchangeable, allowing you to switch between different bands to suit your style or activity. The 45mm Black/Black Nike Sport Band can be easily attached and detached from the Apple Watch case.

6. Functionality: The band is designed to provide a comfortable and secure fit during various activities, including workouts, sports, and everyday use. It is resistant to sweat and water, making it suitable for use during exercise or outdoor activities.

7. Availability: The 45mm Black/Black Nike Sport Band is available for purchase through various authorized retailers, Apple Stores, and online platforms. It may be sold separately or as part of an Apple Watch and band bundle.

Please note that specific availability and compatibility details may vary depending on the region and the Apple Watch model you own.