Community price on backpack.tf: 12.0 keys, last changed 2023-04-01 (3.5y ago). The live quote above, 8.33 keys, is 31% lower and last moved 13d 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 1h ago.
Steam Market asking price: $29.99 — the lowest of one listing for the Massed Flies effect when we looked on 2026-10-07 01:41 UTC (6d 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 8 keys, 21.22 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 Bottle Cap”, with no effect in the name — the effect comes from the individual listing.
Price history
67 observations
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.
Massed Flies Bottle Cap sell price, 2025-09-25 to 2026-10-12: 67 observations, from 12.1 keys to 8.71 keys. Sampled evenly across the range.
Observed (UTC)
Sell
Buy
25 SEP 2025 · 03:29 UTC
12.1 keys
9.84 keys
9 OCT 2025 · 09:55 UTC
11.6 keys
10.4 keys
19 OCT 2025 · 21:47 UTC
11.0 keys
9.88 keys
10 NOV 2025 · 02:02 UTC
11.1 keys
9.92 keys
11 DEC 2025 · 20:58 UTC
13.2 keys
9.15 keys
7 JAN 2026 · 11:42 UTC
12.4 keys
10.1 keys
18 JAN 2026 · 23:27 UTC
10.9 keys
8.37 keys
15 FEB 2026 · 22:41 UTC
11.0 keys
8.08 keys
4 MAR 2026 · 00:42 UTC
10.2 keys
7.26 keys
8 MAR 2026 · 00:43 UTC
10.1 keys
7.47 keys
26 MAR 2026 · 18:08 UTC
10.7 keys
6.93 keys
12 APR 2026 · 14:31 UTC
10.8 keys
6.50 keys
19 APR 2026 · 22:31 UTC
10.6 keys
6.49 keys
7 MAY 2026 · 18:33 UTC
9.91 keys
7.44 keys
22 MAY 2026 · 00:31 UTC
10.4 keys
8.02 keys
2 JUN 2026 · 18:31 UTC
10.5 keys
7.88 keys
15 JUN 2026 · 00:32 UTC
9.80 keys
8.39 keys
29 JUN 2026 · 01:14 UTC
9.81 keys
8.49 keys
5 JUL 2026 · 23:12 UTC
8.87 keys
7.72 keys
19 JUL 2026 · 22:44 UTC
9.26 keys
8.06 keys
3 AUG 2026 · 12:24 UTC
9.91 keys
8.63 keys
21 AUG 2026 · 10:09 UTC
9.74 keys
8.47 keys
21 AUG 2026 · 12:08 UTC
9.77 keys
8.50 keys
21 AUG 2026 · 22:09 UTC
9.88 keys
8.60 keys
22 AUG 2026 · 06:08 UTC
9.79 keys
8.51 keys
22 AUG 2026 · 08:09 UTC
9.74 keys
8.47 keys
22 AUG 2026 · 16:08 UTC
8.36 keys
7.27 keys
23 AUG 2026 · 00:09 UTC
8.57 keys
7.45 keys
23 AUG 2026 · 06:09 UTC
9.81 keys
8.53 keys
23 AUG 2026 · 18:09 UTC
8.94 keys
7.78 keys
24 AUG 2026 · 00:09 UTC
9.83 keys
8.55 keys
24 AUG 2026 · 16:09 UTC
9.78 keys
8.50 keys
7 SEP 2026 · 18:08 UTC
9.81 keys
8.53 keys
11 SEP 2026 · 16:09 UTC
9.67 keys
8.41 keys
13 SEP 2026 · 00:09 UTC
9.67 keys
8.41 keys
16 SEP 2026 · 06:08 UTC
9.41 keys
8.18 keys
29 SEP 2026 · 16:11 UTC
9.21 keys
8.01 keys
4 OCT 2026 · 23:10 UTC
9.98 keys
8.68 keys
7 OCT 2026 · 17:10 UTC
9.85 keys
8.57 keys
12 OCT 2026 · 09:09 UTC
8.71 keys
7.58 keys
Price history in numbers
67 readings since 25 Sep 2025
Over the last 30 days the Massed Flies Bottle Cap's sell price ranged from 8.33 keys to 9.98 keys and is down 7.4% after 7 moves. Over a year it ranged from 7.83 keys to 13.2 keys (down 20.7%). Today's 8.71 keys sits in the lower third of its range: the lowest we have recorded is 7.83 keys (12 Jul 2026) and the highest 13.2 keys (11 Dec 2025). The price has moved 66 times since we began recording it — about once every 6 days.