"Large rodents" joke

I found this blurb in the USAir Gift Catalog ("This catalog is yours to keep.
Please take it with you!") recently. Quoted without permission:
GOPHER-IT
Prevent damage to garden and lawns from burrowing rodents
with Gopher-It, the electronic stake that emits vibration
and sound that's intensely annoying to underground rodents
up to 100 feet in diameter.
Requires 4 "D" batteries, not included.
#26284 Gopher-It $49.95 (3.95)
I suppose for rodents of greater than 100 feet in diameter you need the
nuclear powered version.