An apparatus in combination with a support surface and a flexible substrate, comprising:
- said support surface having a vertically extending corner formed by a longitudinally disposed, upstanding side wall and a transversely disposed, upstanding front wall, and said support surface including a longitudinally extending corner formed by said upstanding side wall and a bottom wall disposed normal to said side wall and said front wall;
- said flexible substrate having a predetermined longitudinal and vertical extent;
- said flexible substrate having a longitudinally extending upper edge, a longitudinally extending lower edge, a vertically extending forward edge, and a vertically extending rearward edge;
- upper attachment means for releasably attaching said longitudinally extending upper edge of said substrate to a longitudinally extending upper edge of said side wall;
- said upper attachment means being permanently secured to said side wall;
- rearward attachment means for releasably attaching said vertically extending rearward edge of said substrate to a vertically extending rearward edge of said side wall;
- said rearward attachment means being permanently secured to said side wall;
- forward attachment means adapted to releasably attach said vertically extending forward edge of said substrate to said transversely disposed front wall, said flexible substrate bending around said vertically extending corner so that air cannot flow between said side wall and said substrate;
- said forward attachment means being permanently secured to said front wall;
- lower attachment means for releasably attaching said longitudinally extending lower edge of said substrate to a longitudinally extending lower edge of said side wall;
- said lower attachment means being permanently secured to said bottom wall;
- an elongate forward hem formed in said vertically extending forward edge of said substrate;
- said elongate forward hem forming an elongate forward loop in said vertically extending forward edge of said substrate;
- an elongate, rigid forward hem loop-occupying member slideably disposed in said elongate forward loop;
- at least one opening formed in said elongate forward hem;
- at least one substrate-tightening strap having a first end disposed in engaging relation to said elongate forward hem-occupying member in registration with said at least one opening;
- at least one winch means mounted on said transversely disposed, upstanding front wall;
- said elongate forward hem disposed in overlying relation to said transversely disposed, upstanding front wall, said substrate overlying said vertically-extending corner;
- said at least one substrate-tightening strap having a second end engaged by said winch means;
- whereby differing substrates are securable to and removable from said support surface without removing said permanently secured attachment means from said support surface;
- and
- whereby operation of said winch means in a first direction coils said at least one strap about said winch means and thus pulls said substrate to inhibit flexing thereof in response to air movement thereacross, and whereby operation of said winch means in a second direction opposite to said first direction loosens said substrate and facilitates removal of said elongate, rigid forward hem-occupying member from said elongate forward hem.