Combination end plate/coupler can be used for individual mounting or slides into position between two fixtures, assuring integrity of row alignment. Optional heavy-duty 10 sleeve couplers can provide additional bracing at fixture junctures. UL Damp Location labels are standard with this series. All 20 watt through 40 watt fixtures are suitable for mounting on low-density cellulose fiberboard surfaces. All T8 high output units need to be suspended a minimum of 1-1/2 from surface. 1/4 turn fastener lock ballast cover onto housing.