M&M's Integral Side Entry Subs are precision-forged, single-body components engineered to outperform standard multi-piece, welded, or flanged designs. By eliminating welds and flanges, the integral construction delivers greater body tensile capacity, added hammer union hang-off strength, and significantly shorter lead times. Complementary pump-in subs and circulating swages are available made-to-order with the customer's choice of hammer union and end connection. At the core of the line is The REF™ sub design — a patent-pending, two-part retention system that resolves the safety risks of traditional flange-bolt attachments. Featuring a threaded hammer union hub and NORD-LOCK locking washers, The REF™ offers superior safety, field-replaceable versatility, and working pressures up to 15,000 psi.