Don’t risk damaging the face of your doors by drilling long holes without our Extension Flushbolt Drill Fixture! This aluminum drill fixture clamps to the corner of your 1-3/4" thick doors to guide a 1/2" diameter bit for extension flushbolt rods. Need to go longer? No problem. Drill a 12" deep hole with the fixture then remove the fixture and you’/ve got a 12" guide hole to work with. You can now use the 48" long bit listed below.