Here is a concise summary of the provided text:
**Title:** The Safety of Cast Saws and a Promotion for Safety Razors
**Main Content:**
* Introduction to cast saws, used to remove casts after bone healing
* Contrary to appearances, cast saws are designed to cut through casts without harming human skin
* High-speed camera footage reveals the saw's oscillating motion, which cuts through rigid casts but simply moves flexible human skin
* Comparison with different types of casts (plaster of Paris vs. synthetic fiberglass) and their interaction with cast saws
* Brief analysis of skin's properties (shear modulus, Young's modulus) based on the slow-motion footage
**Sponsored Segment:**
* Discussion on the drawbacks of proprietary standards (e.g., power tools, razors)
* Promotion for Hensen Safety Razors, highlighting their open standard, quality, and cost-effectiveness
* Special offer for viewers: 100 free blades with the purchase of a razor using a promo code.
Here are the key facts extracted from the text, numbered and in short sentences:
**Cast Saw Facts**
1. A cast saw is used to extract a person from a cast after their bones have healed.
2. Cast saw blades are sharp and fast enough to cut through a cast's hard outer shell.
3. The blade of a cast saw oscillates (moves back and forth) rather than spinning.
4. The oscillation distance of a cast saw blade is approximately 3 mm.
5. A cast saw cannot cut through human skin due to its elastic properties.
**Cast Types and Removal**
6. Traditional casts are made from Plaster of Paris.
7. Plaster of Paris casts take 24-48 hours to dry.
8. Synthetic casts are made from fiberglass with a water-activated resin.
9. Synthetic casts dry in approximately 15 minutes.
10. Cutting a synthetic cast creates less mess than cutting a Plaster of Paris cast.
**Skin and Blade Interaction**
11. Human skin behaves like an underinflated balloon when interacting with a cast saw blade.
12. The skin moves back and forth when the blade touches it, without being cut.
13. The speed of sound in human skin varies by body part (e.g., 10 m/s on the back of the arm, 6 m/s on the back of the hand).
14. The Young's modulus of human skin can be calculated from the shear modulus and Poisson's ratio.
15. The Poisson's ratio of human skin is approximately 0.48.
16. The Young's modulus of skin on the back of the hand is about 100 kilopascals, and on the back of the arm, about 300 kilopascals.
**Miscellaneous**
17. A Dremel (rotary tool) can cut through an underinflated balloon if the balloon is overinflated when the tool is applied.
18. The sponsor of the video is Hensen Shaving, which offers a safety razor with an open standard for blades.