For 3/8 chain with small pitch and 0.050 chain saw chain, 4.0mm file is more suitable. For chains with a pitch of 0.325 and chains with a chain saw pitch of 0.058, a 4.8 mm file is suitable. For chains with pitch of 3/8 and chains with pitch of 0.050 and 0.063, it is suitable to equip with a file of 5.5mm.. Medium-sized machines are suitable for 4.8mm round files, chainsaws and small chainsaws are suitable for 4.0mm files, and large chainsaws are suitable for 5.5mm files.