Uniflex, UniBack and UniHard are all covers that are designed specifically for use in the Unibinder M, Unibinder 8.2 and Unibinder 8.1. 

SteelCrystal, SteelMatt, SteelBack and SteelBook are the equivilent covers designed for use in the Unibind XU138, XU238 and XU338. (also the previous ST series). All off the above covers will work in any Unibind binding machine. For instance the chart below shows the equivelent sizes of the SteelCrystal (clear covers) that can be used instead of the Uniflex covers in the Unibinder series.



Uniflex covers                      SteelCrystal or SteelMatt covers


Small                                                                5mm

Medium                                                           9mm

Large                                                              15mm

XLarge                                                            21mm

XXLarge                                                          36mm


The benefit to using the SteelCrystal over the Uniflex is that the SteelCrystal is avaliable in a compatible product which is on average          20% cheaper than the Uniflex covers. Please contact us for advice