Acme dog whistles are the definitive Gun Dog Whistle.
Each whistle has the appropriate pitch number embossed on the underside, the pitch being identical for each whistle with the same pitch number.
The 210 1/2 produces a high pitch note of 5900 Hz and as such is the highest pitch in the standard ACME range.
Whilst suitable for all dogs this whistle is especially suitable for spaniels. It can also be effective for older and some hard of hearing dogs.