Unlike older roller skates, in-line skates have polyurethane wheels aligned in a single strip like an ice-skate blade.
(in-line skates; have; polyurethane wheels aligned in a single strip like an ice-skate blade) (polyurethane wheels; aligned; in a single strip like an ice-skate blade)
in-line skates polyurethane wheels
have aligned
polyurethane wheels aligned in a single strip like an ice-skate blade
in a single strip like an ice-skate blade