Patent ID: 8347759

Claim:
A wrench including: a metal head having a tunnel defined therein; an isolative coating provided on the head and including an internal annular ridge disposed around the tunnel of the head and an external annular ridge around the internal annular ridge; and a one-way mechanism located substantially in the tunnel of the head and including a tongue located outside the tunnel of the head, a detent partly disposed in the tongue and an isolative button located outside the tunnel of the head; and wherein the button is formed with an annular edge and is pushable to control movement of the detent; when the button is pushed to release the detent, the button blocks substantially completely the tunnel of the head with the annular edge of the button fitted in a gap formed between the internal annular ridge and the external annular ridge; and when the button is released to retain the detent, the annular edge of the button remains in contact with both of the internal annular ridge and the external annular ridge.