Berry's are a good deal price-wise. The 100-rd ones have that plastic connector strap rather than a hinge (same as on MTM 50s).
I don't know if I'm alone in this, but the ones I bought (100-rd .45-10mm) don't stay closed as well as MTM. Never had one pop open, just found myself thinking one might. The 9mm ones are more secure. YMMV.
Anyone else have that problem?