Listings indicate oil filter wrenches are commonly made from steel or aluminum alloy.
Listings show cap-style wrenches use a 3/8" square drive and a 27 mm (1-1/16") hex drive/socket size.
Descriptions list anodized finishes—often black anodizing—on aluminum cap wrenches to resist corrosion and improve durability.
They engage via flutes on the cap face and bottom-edge slots, plus a top opening that accepts a square drive or an external hex socket.
Many listings specify 14 flutes and inner diameters such as 64.5 mm; at least one listing also shows a 70 mm inner diameter.
Listings show 14 flutes on the cap face and bottom-edge slot counts of either 4 or 6.
Specified inner diameters include 64.5 mm (2.54 in) and, in one listing, 70 mm (2.76 in).
Listings describe cap wrenches as non‑OEM aluminum-alloy accessories. Descriptions say the alloy provides torque while protecting fragile plastic filter cartridges and that anodized or black-anodized finishes help resist rust and extend service life.
