# Tools for thinking, to keep

> The Mentarium Field Guide (60 mental models), Thinking Skills for Claude and ChatGPT, and the Decision Journal for Obsidian. One-time prices, instant download.

Canonical: https://mentarium.io/shop.md

Shop

One-time prices, instant download, files you own. 7-day refund if it isn't for you.

 PDF + EPUB

## [The Mentarium Field Guide](https://mentarium.io/shop/field-guide)

60 Mental Models for Clearer Thinking and Better Decisions

$14$19

- 60 mental models, 1 to 2 pages each: in one line, when to use it, trigger questions, an example, the trap
- The 25 biases that break good decisions, each with the model that fixes it
- 12 Model Stacks for real situations: quitting a job, hiring, investing, moving cities and more

Coming soon [Details](https://mentarium.io/shop/field-guide)

 Claude skills (SKILL.md) + ChatGPT instructions

## [Mentarium Thinking Skills](https://mentarium.io/shop/thinking-skills)

12 skills that make Claude and ChatGPT think with mental models

$29

- 12 Claude skills (SKILL.md) for Claude.ai, the Claude apps and Claude Code
- The same 12 as ChatGPT Custom GPT / Project instructions, plus a knowledge file with the Mentarium frameworks
- Install guide for both, in plain steps

Coming soon [Details](https://mentarium.io/shop/thinking-skills)

 Obsidian vault (Notion edition coming soon)

## [The Mentarium Decision Journal](https://mentarium.io/shop/decision-journal)

Log decisions, review them, and see how well calibrated you are

$29

- An Obsidian vault: plain Markdown files you own, no account
- A decision template guided by the Decision Loop, with the Decision Weight Score
- Review Queue: decisions whose review date has come

Coming soon [Details](https://mentarium.io/shop/decision-journal)

## Bundles

Field Guide + Decision Journal

$44

 Coming soon

Thinking Skills + Field Guide

$49

 Coming soon

Mentarium Complete

$69 · save $3

 Coming soon

Bought before? [Resend my download links](https://mentarium.io/downloads). The [Decision Coach](https://mentarium.io/coach) for Claude and ChatGPT is free.