This price has not changed since 2026-08-05 11:12 UTC. It reflects the last observed trade rather than current market value, and this page is excluded from our sitemap for that reason.
Community price on backpack.tf: 7.00–8.00 keys, last changed 2025-12-19 (9mo ago). The live quote above, 6.88 keys, is 2% lower and last moved 1mo ago. They are different measures: the quote is what traders and bots are asking and bidding on the classifieds right now, and it moves for thousands of items every day; the community price is a suggestion accepted by vote, which changes only when someone argues it should. A quote well away from the vote is usually a price that is about to be re-argued. Community prices from backpack.tf, read under an hour ago.
Steam Market asking price: $19.01 — the lowest of 10 listings for the Sandy effect when we looked on 2026-08-29 01:36 UTC (8d ago). This is what a seller is asking, not what anything sold for. Steam pays out in Steam wallet funds, not cash, and Valve takes roughly 15% at the till — so asking prices there run well above the 6 keys, 56.44 ref shown above, which comes from the keys-and-metal market on backpack.tf. The two are different markets and are never blended. Steam lists the item as “Unusual Professor Photon”, with no effect in the name — the effect comes from the individual listing.
Price history
Interactive chart. Press the left and right arrow keys to move along the series, Home or End to jump to either end, Escape to clear.
The key axis converts at today's rate. Prices are recorded in metal, so a line that is flat in keys followed the key rate rather than standing still.
| Observed (UTC) | Sell | Buy |
|---|---|---|
| 20 DEC 2025 · 18:06 UTC | 6.77 keys | 5.34 keys |
| 5 MAR 2026 · 00:42 UTC | 6.72 keys | 5.15 keys |
| 10 MAR 2026 · 10:10 UTC | 6.93 keys | 5.54 keys |
| 11 APR 2026 · 16:32 UTC | 6.95 keys | 5.56 keys |
| 29 APR 2026 · 14:30 UTC | 6.51 keys | 5.09 keys |
| 9 MAY 2026 · 10:33 UTC | 6.89 keys | 5.01 keys |
| 17 MAY 2026 · 20:35 UTC | 7.20 keys | 5.85 keys |
| 10 JUL 2026 · 08:44 UTC | 6.26 keys | 5.58 keys |
| 20 JUL 2026 · 14:44 UTC | 6.79 keys | 5.90 keys |
| 27 JUL 2026 · 00:46 UTC | 6.67 keys | 6.10 keys |
| 5 AUG 2026 · 11:12 UTC | 6.88 keys | 6.31 keys |
Price history in numbers
11 readings since 20 Dec 2025The price has not been re-read inside the last 30 days. Over a year it ranged from 6.26 keys to 7.20 keys (up 1.6%). Today's 6.88 keys sits in the middle of its range: the lowest we have recorded is 6.26 keys (10 Jul 2026) and the highest 7.20 keys (17 May 2026). The price has moved 10 times since we began recording it — about once every 23 days.
| Window | Low | High | Change | Moves | Readings |
|---|---|---|---|---|---|
| 90 days | 6.26 keys | 6.88 keys | +9.9% | 3 | 4 |
| a year | 6.26 keys | 7.20 keys | +1.6% | 10 | 11 |
Details
| SKU | 31569;5;u392 |
|---|---|
| Last price change | 2026-08-05 11:12 UTC |
| Key rate when recorded | 64.33 ref |
Same effect, other items
the effect across the catalogue| Item | Value | Updated |
|---|---|---|
| 381 keys | 9mo ago | |
| 350 keys | 3mo ago | |
| 184 keys | 22d ago | |
| 160 keys | 9mo ago | |
| 104 keys | 1mo ago | |
| 100 keys | 9mo ago | |
| 70.0 keys | 9mo ago | |
| 65.0 keys | 6h ago | |
| 60.0 keys | 9mo ago | |
| 60.0 keys | 9mo ago |
Other effects on the Professor Photon
same item, different effect| Item | Value | Updated |
|---|---|---|
| 81.2 keys | 14h ago | |
| 38.0 keys | 18h ago | |
| 10.1 keys | 1mo ago | |
| 9.55 keys | 22d ago | |
| 7.46 keys | 6d ago | |
| 7.22 keys | 26d ago | |
| 7.13 keys | 15d ago |
Priced similarly
across the catalogue| Item | Value | Updated |
|---|---|---|
| 6.90 keys | 15d ago | |
| 6.90 keys | 15d ago | |
| 6.90 keys | 5d ago | |
| 6.88 keys | 19d ago | |
| 6.90 keys | 15d ago | |
| 6.88 keys | 2mo ago | |
| 6.90 keys | 7d ago | |
| 6.90 keys | 15d ago |