When you are choosing a trimmer, you need to decide between gas and electric models. Gas models can be taken all over your lawn because you are not tethered to a cord. At the same time, they will emit fumes when you are using them. You should consider wearing a face mask or goggles if you believe the fumes will irritate. Electric models use a cord that you need to plug in outside, and you should use a cord clip to keep the cord off the ground. These models are much safer to use but the range is limited because the cord is only so long.