Access roll up, velcro side seals and just clamp-on side frames. Second one I've had, no problems with wear, tearing or fading over the 4+ years on the first one.
Don't really need much security, great for covering the bed and keeping things dry. Also appears to aid somewhat in highway fuel economy vs an open truck bed. Rolls up in seconds, if I need to tote something big.
Always had alum. or fiberglas caps before, probably never own another one.
If three or more people think you're a dimwit, chances are at least one of them is right.