When to Rotate a Metal Seed Backup
Signs that your stamped or engraved seed phrase plate needs replacement, and how to schedule rotation without exposing your words unnecessarily.
Read article →Cold Wallet Custody · Yongin, KR
Your offline holdings deserve a maintenance calendar, not a forgotten drawer
System Maple Line provides session-based cold wallet maintenance for individuals and family offices who keep Bitcoin and other assets in hardware wallets, paper backups, and air-gapped storage. We schedule, document, and walk you through each review so your keys stay current without ever going online.
Book a custody review View session calendar
Scheduled sessions for long-term holders
Cold storage fails quietly. Seed phrases fade, firmware drifts out of date, and family members forget where backups live. Our maintenance calendar turns custody into a recurring appointment with clear steps and written records.
Quarterly custody review
Flagship session covering device health, backup integrity, passphrase rotation guidance, and inheritance documentation updates. Conducted in person at our Yongin office or via guided remote walkthrough.
Hardware wallet audit
Focused examination of your Ledger, Trezor, Coldcard, or other device. We verify genuine firmware, test recovery on a spare unit, and note any manufacturer advisories relevant to your model.
Recovery readiness check
Simulated recovery drill using your backup materials in a controlled setting. Identifies gaps in your process before an actual loss event forces the question.
Upcoming maintenance windows
Open slots for new client onboarding and returning quarterly reviews. Sessions require advance booking and a brief intake form.
Sep 12, 2026
Quarterly review
Two seats available for returning clients. Morning block, 09:00–12:00 KST.
Sep 19, 2026
New client intake
Initial custody assessment for holders with one or two hardware wallets. Afternoon block.
Oct 3, 2026
Recovery drill
Group session limited to four participants. Bring your backup kit; we provide the test environment.
From the journal
Field notes on cold wallet care, backup rotation, and custody decisions for Korean residents holding assets offline.
Firmware Updates on Air-Gapped Devices
A practical walkthrough of updating Coldcard and similar air-gapped hardware wallets without connecting to the internet — what to verify before and after.
Read article →
Documenting Custody for Family Members
What to include in a written custody summary so spouses and heirs can locate devices and backups without learning your seed phrase prematurely.
Read article →What holders say after their first review
After three years of buying hardware wallets and stuffing seed cards in a safe, I finally understood which backup was current. The written summary from the session is now with my attorney.— Hyeon-jun R., quarterly review client, Suwon
The recovery drill was uncomfortable in the right way. I discovered my wife's copy of the passphrase used an old format. Fixing it took twenty minutes; not finding out would have cost far more.— Margaret L., recovery readiness session, Seoul
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