The investigation has been upgraded to Engineering Analysis EA 13-001 for further study. The Office of Defects Investigation (ODI) opened this investigation based on 25 reports from consumers that alleged difficulty in unlatching the harness buckle on their subject child seat.Since opening the investigation, ODI has received 55 additional reports.Consumers state that excessive force and/or effort is required to push the button to unlatch the harness.Some reported not being able to unlatch the buckle at all and were forced to remove their child by pulling them through the still buckled harness, or in some cases, by cutting the harness straps.The subject child seats utilize two different types (designs) of harness buckles, the Signature and the QT types, both of which are subject to the investigation.Each buckle type operates differently and has dissimilar latching and actuating mechanisms.The Signature buckle has a sliding release button that must be pushed downward to release the harness, while the QT buckle has a button that must be pushed inward to be released.The ODI reports can be reviewed at http://www-odi.nhtsa.dot.gov/owners/SearchNHTSAID under the following identification (ODI) numbers: 10361369, 10366522, 10366645, 10366950, 10383056, 10397307, 10397449, 10406827, 10410574, 10413648, 10413817, 10414471, 10418155, 10421053, 10428246, 10430498, 10433600, 10444493, 10444593, 10454295, 10454393, 10454450, 10455029, 10456547, 10463507, 10466250, 10467797, 10473717, 10475529, 10475529, 10477267, 10478809, 10481182, 10481219, 10481233, 10481236, 10481243, 10482654, 10482941, 10483551, 10483732, 10483940, 10485417, 10486165, 10487751, 10487824, 10488855, 10489296, 10489536, 10489662, 10490292, 10491819, 10493243, 10493351, 10493614, 10493620, 10493649, 10493668, 10493716, 10494411, 10494567, 10494580, 10494635, 10494769, 10494876, 10495042, 10495130, 10495301, 10496034, 10496063, 10496146, 10496344, 10496470, 10497637, 10497771, 10498293, 10498308, 10498468, 104985