# 4.5.2 Entering thumb hole size

<span style="font-family: monospace; color: #6b7280;">4.5.2</span> <span style="border: 1px solid #d1d5db; color: #4b5563; padding: 2px 8px; border-radius: 3px; font-size: 0.85em;">thumb</span>

For a **round** thumb, the hole size is a single value entered on the spec sheet. The thumb section records both the **O.D.** (the drill/hole size) and, when a thumb insert or slug is used, the **hole size** the bowler's thumb actually sits in — the two are different values whenever an insert or slug is involved.

- ✅ **Bare thumb:** the O.D. is the hole drilled directly into the ball.
- ✅ **Thumb slug or insert:** the O.D. is the pilot hole drilled to accept the slug/insert; the **hole size** is the finished opening the thumb sits in. Record both — don't put the same value in both fields.
- ✅ For an **oval** thumb, the size is not a single value — it comes from the four oval inputs (see 4.6.1), so this single size field does not apply.

## 🛠️ Entering Thumb Size in Spectre Cloud

1. Confirm the thumb shape is set to **Round** (see 4.5.1).
2. Enter the thumb **O.D.** (hole/drill size).
3. If a slug or insert is used, enter the finished **hole size** as well.
4. Proceed to pitch and insert entry.

⚠️ **Verify with your Spectre team:** confirm the exact field labels for thumb O.D. vs. hole size, and the unit (fractional/decimal inches).

### Related Sections

- 4.5.1 — Selecting the thumb hole shape (Round or Oval)
- 4.5.3 — Entering vertical and lateral pitch for thumb
- 4.5.4 — Thumb insert type and size
- 4.4.2 — Finger inserts
- 4.6.1 — Oval thumb inputs (for oval hole sizing)

**Tip:** Thumb size is the measurement most likely to change between visits — with temperature, time of day, and swelling. Don't carry a thumb size forward from an old sheet without re-checking it.