PG11 Size 5-10mm is ideal for passing up to 4 large Thermopro temperature probes into the grill or smoker. This requires a 3/4" diameter hole, so you can use cheaper titanium step drill bits that go up to 3/4" to make the hole. Be sure to drill from the inside out and use masking tape to protect the surface being drilled. It doesn't wrap all the way around the wires, but it does make the hole small enough that you don't have to worry about enough smoke loss. Although intended for a different application, they make excellent probe connectors. So much so that you'll find them listed as "Barbecue Probe Port" by vendors offering wildly overpriced to convince you they're made for that purpose.