length of fingers 4 is too short then connected panels 1 may disengage too easily on the other hand if the length of the fingers 4 is too great then it is difficult to achieve a manual snap fit for example in such circumstance to achieve a snap fit tools such as a pry bar and or a hammer may have to be used and in the use thereof one or both panels 1 may be damaged or the mere attempt to force a snap fit with fingers 4 that are too long may damage fingers 4 and or arms 5 it has been found that for typical substrate materials such as pvc or reprocessed thermoplastic an arm length for arm 5 in the range of about u00bd inch to about 1 inch and preferably about u00be inch and an arm thickness for arm 5 in the range of about 0 08 inch to about 0 1 inch and fingers 4 with a length in the range of about 0 110 inches to about 0 230 inches are workable more preferably the length of fingers 4 would be in the range from about 0 130 to about 0 160 inches as an alternative to snap fitting as described above as shown in fig4 adjacent panels 1 may be connected by vertically sliding them together while the.