Last year, Cat launched the first phone equipped with a FLIR sensor for measuring temperature. This year it's back with two new mid-range smartphones designed to survive the harshest work environments. The S41 and S31 are both durable phones, and both priced closer to the budget end of the market than the flagship end. 

The Cat S31 is the follow up to the S30 (no surprise there) and isn't just designed to survive in tough environments, its battery can keep going for days. Similarly, the S41 is the natural successor to the S40. 

As well as being IP68 rated against water and dust ingress, both phones are resilient and can survive 1.8 metre falls on to concrete. Like only a handful of phones they also bear the MIL SPEC 810G durability certification. That means there's very little they won't get through.

Whether you're in an outdoor trade, work in construction around lots of dust or enjoy extreme sports, these phones will get through it all. 

Of course, there are differences between the two models, mostly in terms of hardware specifications. 

CATCAT S31 and S41 image 3

Starting with the the S41; this is the battery champion of the two. It has a huge 5,000mAh battery that CAT says will last 44 days in standby, and handle up to 38 hours of 3G talk time. It can also be used as a battery pack to charge other devices, using the Battery Share feature. 

It runs Android Nougat, powered by a MediaTek octa-core 2.3GHz processor and 3GB RAM. It also has 32GB internal storage and support for MicroSD cards up to 2TB.

The full HD 5-inch screen should be among the sharpest out there in the mid-range market thanks to its impressive pixel density. More importantly, you'll be able to use it with wet fingers or while wearing gloves. 

Its grippy, textured design makes it easy to keep a hold of in challenging environments, while the addition of the physical shortcut button makes launching specific functions much easier. This is programmable, and can be used for virtually anything. 

The 8MP camera on the back should be perfectly adequately adequate and is partnered with a 2MP front-facing camera. 

CATCAT S31 and S41 image 2

As for the S31 is slightly smaller, with a 4.7-inch 720p display and a 4,000mAh battery. Like the S41, the screen is usable even if you're wearing gloves, or have wet fingers. 

Unlike its big brother, the S31 has quad-core Qualcomm processor, 2GB RAM and just 16GB internal storage. This is expandable via MicroSD card. 

The CAT S41 will be available from Cat's online store from 31 August for €449, while the S31 will come later this year for €349. UK Pricing hasn't been announced yet.