I bought these as spares for my new quad navigator. I had to replace my four year old quad coaster because the front wheels were worn out and MGI does not stock replacement parts for units that old, even though such replacement parts would not normally be needed for several years after purchase. I also have previously complained that there is a serious design defect with the battery cable. Because when in place the battery cable is bent. I have twice replaced an otherwise functioning battery because of a short in the cable at the point the cable connects to the battery, As the battery cable connects to the power delivery point in the battery and the battery is sealed, the cable cannot be replaced, MGI should redesign these batteries so that the cable that connects to the battery can be replaced by a plug in cable. The failure of a $400 battery due to a short in a $10 part is silly.