ECX) - Pearl's most popular series of drum kits, and the most popular set ever sold (the one millionth Export kit was produced in 1995). The first generation of Export drums were made of 9-ply Philippine mahogany, and the newer were made with 6 plies (7.5mm) of Poplar, with the ECX series being made from maple, and come standard with Pearl's ISS tom mounting system. They were discontinued and replaced by the Vision series (VMX - 6ply maple, VBX - birch, VSX, VX) and later reintroduced in 2013 (as the EXX) to replace the Forum line. Session - The successor of the World Series, Prestige Session Elite (SLX), Prestige Session (lacquered) and Performance Session (covered) were introduced in 1991. The shells were 7-ply, 7.5mm: One inner ply of birch, one outer ply of birch, and five middle plies of mahogany. Toms had Superhoops. Rack toms had I.S.S. Mounts. Prestige Session and Performance Session still retained the WLX designation and came with traditional double lugs, while SLX had high tension lugs and came with better hardware. In 1994, the SLX became the SPX Prestige Session (lacquered) and SX Session (wrapped) Series. The SX shells were 8 ply Mahogany and Laminate while the SPX shells were 7 ply birch and mahogany. In 1997 SRX Prestige Session Select replaced SPX and SX line. The shells were 7 ply maple and mahogany. In 2001 SRX Prestige Session Select became the SRX Session Custom, 6-ply all-maple shells with the OptiMount suspension system and 2.3mm SuperHoops II. In 2004 SRX became the SMX Session Custom 6 ply 100% maple series, and SBX Session Custom all birch. Sessions were discontinued in 2006 to make way for Vision series and MCX Masters Custom in 2007. These drums were extremely popular, but expensive. The Session line was later reintroduced in 2012 as the Session Studio Classic. Masters - Masters series became available on the market in 1993, and included sets made of maple and birch, as follows: Masters Custom MMX (4-ply, 5mm maple shells with reinforcement rings), Masters Custom Extra CMX (6-ply, 7.5mm maple), Masters Studio MBX (4-ply birch with reinforcement rings), Masters Studio Extra CBX (6-ply, 7.5mm birch). In 1997 Masters Mahogany Classic MHX with 4-ply, 5mm African Mahogany shells and 4-ply, 5mm maple reinforcement rings was introduced. In the same year CMX was renamed Masters Custom Extra MRX, while Masters Studio Birch MBX was discontinued. In 1999,