carpet knives

with a very good thumb guard

• https://www.amazon.com/dp/B0C54TTFYG — XW
• https://www.amazon.com/dp/B0CTVD7K4L — Capitol (It currently takes 14 days for shipping.)
  • This is the only version with two different holes, allowing it to hold both carpet blades and utility blades.
• https://www.amazon.com/dp/B0F8PLGLCQ — generic brand
• https://www.amazon.com/dp/B0CTVDN346 — Capitol — an "underlayment" knife, it's kind of odd

with a large hump to protect the thumb

• https://www.amazon.com/dp/B0DCLH56NF — Roberts
• https://www.amazon.com/dp/B00L2MQ0IQ — Roberts
• https://www.amazon.com/dp/B00FGYCY1I — Beno J Gundlach
• https://www.amazon.com/dp/B071S6GTQX — Finch & McLay, Inc.
• https://www.amazon.com/dp/B00TBK3YNK — Kraft Tool

retractable

• https://www.amazon.com/dp/B0CBBL4KCP — XW
• https://www.amazon.com/dp/B0051XQECE — I'm not sure about those reviews.
  • https://www.amazon.com/dp/B003553F2C

folding

• https://www.amazon.com/dp/B08X15PHMY — XW

knife is thin near the blade

• https://www.amazon.com/dp/B07L2DXB5P
• https://www.amazon.com/dp/B08X15PHMY — folding, brand: XW