The Pulsar half opal quartz bucket banger is a pure quartz 45 degree nail with a half opal quartz bucket for excellent heat retention and a groundless joint for a more solid connection. The bucket opening is beveled to allow for a tight seal with your 20mm (or larger) carb caps. Since half the bucket is opal quartz, it will retain heat for much longer than regular quartz banger. The inner bucket diameter measures 14mm.