The continuously flow-staged and pressure-boosted seawater reverse osmosis-closed circuit desalination technology of low energy, high recovery irrespective of the number of elements per module and wide flux range characteristics opened the door to the design of small compact single module units with two to four elements (8″) for flexible permeate production of up to 100 m3/d. The design features and performance characteristics of such compact MEn (n = 2–4) units are analyzed in the present paper by a theoretical model in terms of flow, flux, energy, power, recovery, permeate production, and quality as well as the time period of the consecutive sequential process. The theoretical model- simulated performance results with 32,000 ppm NaCl, equivalent to typical Ocean water of 35,000 ppm, are consistent with experimental results and reveal high recovery (50%) over a wide flux range (10–25 lmh) which extrapolate to the energy of 1.24 kWh/m3 (85% eff. of HP and 75% eff of CP) and1.05 kWh/m3 (100% eff of HP and 100% eff of CP) under near-zero flux conditions demonstrating performance at the theoretical minimum energy level unmatched by any conventional technique. The unique performance characteristics of the small compact units under review makes them ideal for marine applications (water supplies to cargo vessels and oil rigs) as well as for the entire water supplies of shore-line communities with population of up to 1,000 residents and the drinking and cooking water requirements of as many as 10,000 residents. Moreover, the wide range flux performance capability of said units make them ideal for integration with renewable energy sources through solar panels and/or small wind turbines for low- cost seawater desalination by means of free and clean renewable natural energy.