3/8" 1.3 52 Similar to Stihl Picco and Oregon 91. PLEASE CHECK THE DETAILS OF YOUR OLD CHAIN WITH THE ABOVE INFORMATION TO ENSURE IT CORRECT FOR YOUR CHAINSAW. Features include Archer saw chain is ideal for the semi professional and occasional user. The saw chain is a semi chisel saw chain which is of benefit to users who hand sharpen the chains as it is more forgiving of filing errors, also because it is a semi-chisel chain it will stay sharper for longer. The chain is a competitive price due to the quantity we purchase and is packaged for internet sales and not because of the quality. These chains requires a 4mm files for sharpening. If you are unsure of the saw chain you require please email firstname.lastname@example.org with the details of your saw.