Machined from solid steel and offred with lug for installation, or drilled for a clean-out screw, included. We offer 7/16" drums for use with the Bedford, small Siler, and other small locks, and 1/2" drums for the large Siler, most L&R locks, and others. Drums predrilled for the nipple are are threaded for 1/4-28 nipples, unless specified otherwise. We suggest that you order your drum not drilled for nipple. Use our Drum Drilling Jig to install the nipple. It is very easy to use our jig to drill and tap the nipple, but it is often difficult to index a pre-drilled drum to the exact desired position.