Coros Apex 4 42mm Straps, Cases, & Screen Protectors

How to choose the right strap for your Coros Apex 4 (42mm)

One of the biggest advantages of the 42mm version of the Apex 4 is its compact and unobtrusive profile. To get the most out of the watch’s heart rate monitor and comfort, you should adapt the strap to your activity:

• If you’re trail running, doing an ultra-marathon or hiking: Then a lightweight strap in braided nylon or woven fabric with a stepless Velcro fastening is the superior choice. Nylon allows the skin to breathe during prolonged exertion, and the stepless adjustment lets you secure the watch with millimetre precision. This prevents the watch from shaking, thereby eliminating inaccurate heart rate readings (known as ‘cadence lock’) whilst running.
• If you swim, do triathlons or train in mud: In that case, we recommend a sports strap made of high-quality silicone or fluoroelastomer. Unlike fabric, silicone does not absorb water. It is extremely durable, flexible and can be easily rinsed clean straight after a muddy mountain bike ride or a dip in salt water.
• If you wear the watch round the clock for sleep and recovery data: Then, once again, a soft fabric strap is best. It creates no hard pressure points against your wrist whilst you sleep, ensuring that HRV and sleep measurements can continue undisturbed and comfortably throughout the night.
• If you want a seamless transition to everyday life and the office: You can easily transform your multisport watch into a stylish everyday accessory by switching to a classic leather strap or a brushed stainless steel bracelet. Perfect for days off.

Protect the sapphire crystal and case

Although the watch is built with premium materials, the screen is always at risk when climbing or orienteering in dense forest. By applying a tempered glass screen protector, you ensure the display remains scratch-free without compromising the touchscreen’s responsiveness or brightness. Complete the look with a protective case to preserve the case’s finish.

Frequently asked questions about Coros Apex 4 (42mm) accessories

What size strap fits the Coros Apex 4 (42mm)?

This specific model uses standardised straps with a width of 22 mm. All straps in this category are fitted with so-called ‘quick-release’ pins, allowing you to click the strap on and off in seconds without any tools.

Does the strap affect the watch’s heart rate monitoring?

Yes, very much so. An optical heart rate monitor requires constant contact with the skin without being too tight and restricting blood flow. Many athletes therefore prefer adjustable textile or nylon straps, as they can be fine-tuned better than traditional straps with fixed holes.

Do the screen protectors fit both the 42mm and 46mm versions of the Apex 4?

No. As the screen size differs between the two models, you must ensure you purchase a screen protector that is precisely cut to fit the 42mm case. All protectors and cases on this specific page are guaranteed to be moulded to fit the Coros Apex 4 (42mm).