Tibetan Phone Bell and Timer, $149.95
"The timer can be set from 1 to 99 minutes. The striking mechanism can be set on high or low... the timer counts backwards to zero and strikes the bowl-gong. Strikes gradually increase in frequency over a 10 minute period..."
PrannaTimer, from $175 with singing bowl
"Our timers are simple and elegant, use no batteries or electricity and are made of beautiful hardwoods. ... Pull back the free swinging hammer and attach it to an incense stick. When the incense burns away, the stick swings into a singing bowl, which rings to signal the end of the sit. ... The incense sent with the timer ... will burn for over an hour, but most meditators will break the incense to sit for shorter periods."
Dayasa, from €489 with singing bowl
"[A] hand-made singing bowl that is resting on a beautifully shaped wooden corpus. At the set time, a clapper strikes the bowl and creates a gentle gong sound..."
'Just About Now' by Maarten Baas with Laikingland, £3,600.
"[A] sand timer that indicates the passing of time with the sounding of a gong... more or less after the amount of time you indicated."