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U-Power Mercia S3 HRO HI CI Leather Vibram Safety Boots (This item)
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PRODUCT FAQs
Yes. With both HRO heat-resistant outsole protection and CI cold insulation, the Mercia is specifically suited to steel plants and other settings with extreme temperature exposure.
The self-forming WOW insole distributes body weight evenly to ease pressure points, while the breathable air tunnel lining helps manage moisture across long, physically demanding days.
HI indicates the outsole has been tested for heat insulation, meaning it can be exposed to hot surfaces for a set period without significant heat transferring through to the foot.
Choosing the right safety footwear is about more than selecting a comfortable pair of boots or trainers. The safety rating tells you the level of protection the footwear has been independently tested to provide under EN ISO 20345, the principal European standard for occupational safety footwear.
What is EN ISO 20345?
EN ISO 20345 specifies the requirements for safety footwear fitted with a protective toe cap capable of resisting a 200-joule impact and a 15 kN compression force. Additional classifications identify further protection for different working environments.
Main Safety Ratings
Rating / Typical Protection
SB / Basic toe protection.
S1 / Toe protection, anti-static properties, heel energy absorption and fuel oil resistant outsole.
S1P / S1 plus penetration-resistant midsole.
S2 / S1 plus water-resistant upper.
S3 / S2 plus penetration resistance and cleated outsole.
S3S / Updated EN ISO 20345:2022 classification with toe protection, penetration resistance and cleated outsole.
S7 / High-performance waterproof safety footwear meeting additional water protection requirements.
Common Markings
Code / Meaning
ESD / Electrostatic discharge protection.
FO /Fuel oil resistant outsole.
SR / Slip resistance tested under EN ISO 20345:2022.
CI / Cold insulation.
HI / Heat insulation.
HRO / Heat-resistant outsole.
SC / Scuff cap abrasion resistance.
Choosing the Right Safety Rating
S1 and S1P are commonly chosen for indoor workplaces such as warehousing and manufacturing. S3 and S3S are popular for construction, engineering and outdoor work where greater protection and grip are required. If waterproof performance is important, choose footwear where this feature is specifically stated and the boot has a waterproof lining such as Gore-Tex, Cofra-Tex or Sympatex.
More Than a Safety Rating
The safety rating is only part of the decision. Consider comfort technologies, upper materials, weight, fastening systems, outsole design and whether features such as ESD protection or waterproof construction are required for your working environment.
Other Questions
Is S3 better than S1P?
Not always. S3 adds water-resistant upper requirements and a cleated outsole, making it better suited to many outdoor environments.
What does ESD mean?
ESD footwear helps control static electricity and is commonly used in electronics, manufacturing and other static-sensitive workplaces.
What is the difference between S3 and S3S?
S3S is the updated classification introduced with EN ISO 20345:2022. It reflects revised testing and terminology
while maintaining a high level of protection.
