The TritBit takes a 3.0x22.5mm (or 3.0x23.0mm) tritium vial. This product will require some cleaning up inside, which is easily done with a handheld drill. See my tritium vial installation page for instructions.
The TritBit is available in Shapeways' Stainless Steel, Gold Plated and Antique Bronze materials and can be purchased here: http://shpws.me/oVwR