The midsole materials of safety shoes are diverse, and different materials have their own advantages in performance. Here are some common types of midsoles and their characteristics, and choose the ones based on the requirements of the working environment:

1. Kevlar® midsole 
Features: Made of high-strength aramid fibers, it possesses outstanding puncture resistance (able to withstand a puncturing force of over 1100N), and is also lightweight, making it suitable for environments with many sharp objects such as construction and mining.
Advantages: Resistant to high temperatures and tearing, but with poor breathability. 

2. Polyurethane (PU) midsole 
Features: Low density, soft texture, providing excellent shock absorption and elasticity, suitable for occupations requiring prolonged standing or walking (such as logistics and warehousing).
Advantages: Resistant to oil and chemicals, environmentally friendly and biodegradable, but prone to hydrolysis when exposed to water for a long time. 

3. EVA (Ethylene-Vinyl Acetate) midsole 
Features: Lightweight and highly elastic, commonly used in protective shoes that require shock absorption (such as for light work or daily commuting).
Disadvantages: Poor wear resistance and prone to absorbing water, not suitable for oily or humid environments. 

4. TPU (Thermoplastic Polyurethane) midsole 
Features: Combines the wear resistance of rubber and the easy processability of plastic, with outstanding flexibility. Suitable for scenarios involving high-frequency movements (such as firefighting and rescue).
Advantages: High mechanical strength, but with average breathability and a relatively heavy weight. 

5. Dual-density PU midsole 
Features: Through the layering design of different densities of PU, it strikes a balance between support and comfort, meeting the national standards for tear resistance and bonding strength (such as the 30,000 times bending test).
Application: The top choice for high-fatigue environments (such as production line workers).

 
6. Steel bottom / Composite stab-resistant layer 
Features: Built-in steel sheet or composite fiber layer provides dual puncture resistance protection, meeting the national standard of ≥1100N. Commonly used in power and mining operations. 

Suggested Choices: 
Bulletproof protection requirement: Choose Kevlar® or steel midsole as the priority.
Comfort and shock absorption: PU or dual-density PU are better options.
Lightweight operation: EVA is suitable for dry environments, while TPU offers a balance between performance and durability.

In the next episode, let's talk about different techniques.