Why S1P is chosen so often
S1P combines the two things that matter most in most workplaces: protection for the toes and for the sole of the foot. Because there's no requirement for a water-repellent upper, S1P shoes stay light and breathable, and there are many sporty models with a sneaker-like fit. For production, installation, technical work and logistics, it's therefore the most practical class.
The penetration-resistant layer comes in steel or textile. Textile, designated S1PS or S1PL, is lighter, doesn't conduct cold and is tested with a thinner nail in the S variant.
Indoors or outdoors?
S1P is made for dry environments. If you work outdoors, on a construction site or in the mud, choose S3: it has the same protection plus a water-repellent upper and a profiled sole.