S4 and S5 are safety-footwear categories, while O4 and OB are occupational-footwear categories. The most important difference is toe protection: EN ISO 20345 safety footwear includes a protective toe cap, while EN ISO 20347 occupational footwear does not carry that safety toe-cap requirement. S5 adds penetration resistance to the S4 protection package; O4 adds specified workplace properties to basic occupational footwear.
Do not select a boot from the category name alone. Always check the standard edition, the complete marking string, optional property symbols, the exact certificate model and the buyer’s workplace risk assessment.
Buyer Comparison Table
| Category | Footwear family | Protective toe cap | Penetration-resistant insert | Typical procurement use |
|---|---|---|---|---|
| OB | Occupational footwear | No safety toe-cap requirement | Not part of the basic category | General wet-work footwear where a safety toe cap is not required |
| O4 | Class II occupational footwear | No safety toe-cap requirement | Not part of the O4 category | Wet workplaces needing the O4 property package without safety toe protection |
| S4 | Class II safety footwear | Yes | Not part of the S4 category | Wet workplaces requiring safety toe protection but not underfoot penetration protection |
| S5 | Class II safety footwear | Yes | Yes | Wet workplaces where both toe protection and penetration resistance are specified |
This table is a selection guide, not a substitute for the full standard. Property symbols such as FO and SR must be read separately. They should not be treated as automatic features of every boot in a category.
OB: Basic Occupational Footwear
OB belongs to EN ISO 20347 occupational footwear. It is used when the buyer does not require the safety toe protection associated with EN ISO 20345.
A buyer should still specify the work environment. Water exposure, outsole design, resistance to particular contaminants, temperature, fit, size range and cleaning requirements may matter even when a protective toe cap is not required.
The supplied Litai evidence includes selected OB FO or OB FO SR models under EN ISO 20347:2022+A1:2024. Those symbols and model scopes come from the individual certificates; they cannot be extended to every occupational boot.
O4: Occupational Footwear for Wet Workplaces
O4 is also an EN ISO 20347 category for Class II footwear, which commonly includes all-rubber or all-polymeric construction. It adds specified properties such as antistatic behaviour and heel energy absorption to the basic occupational requirements. The exact standard edition and marking must be checked.
O4 does not become safety footwear simply because it is tall, heavy or used in industry. If the risk assessment calls for a protective toe cap, the buyer should evaluate an EN ISO 20345 safety category instead.
Litai’s supplied certificates list selected LT-102, LT-103, LT-104, LT-107, LT-118H, LT-318H, LT-601 and LT-701 configurations in O4 categories. Some certificates add FO or SR. The exact combination differs by model.
S4: Safety Toe Protection Without the S5 Insert
S4 is an EN ISO 20345 safety-footwear category for Class II footwear. It includes the safety toe-cap requirement and the S4 property package, but it does not include the penetration-resistant insert that distinguishes S5.
S4 can suit wet industrial, food-processing, agricultural or cleaning applications when toe-impact risk exists but underfoot penetration protection is not required by the workplace assessment. That is an application example, not an automatic recommendation.
Selected Litai LT-series models are listed on supplied EU, UKCA and Australian documents in S4 categories. Buyers must match the exact quoted code, category and additional symbols to the document.
S5: Safety Toe Plus Penetration Resistance
S5 builds on S4 by adding penetration resistance. It is commonly specified where sharp objects or underfoot hazards form part of the assessed risk, such as some construction, waste-handling or heavy-maintenance environments.
Do not assume every penetration-resistant component is identical. The current standard edition and the certificate marking determine the tested construction and applicable symbol. Ask whether the quoted design uses a metallic or non-metallic insert and whether that design is the one covered by the certificate.
The supplied Litai evidence includes selected LT-series S5 models under EN ISO 20345 and selected model families under Australian StandardsMark Licence SMK41505. This is model-specific evidence, not a catalogue-wide claim.
Why FO and SR Need Separate Attention
FO and SR are additional property markings shown on some certificates:
- FO relates to fuel-oil resistance of the outsole under the applicable test method.
- SR identifies the slip-resistance marking used by the applicable current standard.
Older documents may show SRA or SRC instead. Do not translate an older slip code into a newer SR claim without checking the standard edition and report. A category such as S4 or O4 does not automatically prove every optional property.
Application Examples
| Buyer situation | Starting category to evaluate | Questions to confirm |
|---|---|---|
| Food-processing washdown with no toe-impact risk | O4 or another occupational category | Is safety toe protection required? What floor and cleaning agents are present? |
| Agriculture with machinery and toe-impact risk | S4 | Is underfoot penetration also a risk? Is FO or tested slip resistance required? |
| Construction site with sharp debris | S5 | Which penetration-resistance construction and certificate apply? |
| General rain use without occupational protection requirement | OB or non-certified rain boot | Is the product PPE in the destination market and contract? |
The final choice should come from the buyer’s hazard assessment, destination rules and contract—not from a generic industry label.
What to Request from the Supplier
- Exact product code and construction.
- Standard number and edition.
- Complete category and property marking, including FO, SR, SRA or SRC where applicable.
- Model-specific certificate or StandardsMark schedule page.
- Declaration of Conformity where required.
- Toe-cap and penetration-insert construction for the quoted model.
- Size range, colour and private-label options that stay within the approved type.
- Current material or batch reports required by the destination market.
- For DR/DF codes, an approved relationship to the certified LT code before using a certification claim.
Buyer FAQs
Does S5 mean “better” than S4?
It means S5 includes penetration resistance in addition to the S4 package. It is appropriate only when that protection matches the risk and purchasing specification.
Does O4 have a safety toe cap?
O4 is occupational footwear under EN ISO 20347 and does not carry the EN ISO 20345 safety toe-cap requirement.
Is FO automatically included in S4, S5 or O4?
Do not assume so. Check whether FO appears in the complete marking and model certificate.
Are SRA, SRC and SR interchangeable?
No. They come from different standard editions and test schemes. Quote the marking printed on the current model document.
Can a DR or DF code use an LT certificate?
Only after the company has an approved model cross-reference and the conformity evidence supports the exact product. Visual similarity is not enough.
Request the Correct Configuration
Send the destination market, work application, required category, floor and contaminant conditions, size range, quantity, colours and private-label requirements. Litai can then identify candidate LT configurations and provide the available model-specific documents for buyer review.
B2B inquiries: info@litaishoes.com
