Matchbox Lesney 49 a M3 Military Personnel Carrier or Half-track Treaded Grey Tracks.
2 per model. Sold only as pairs so that they both match. This size track available in grey, black, or green.
These have the same wheelbase axle centres as the 8 & 18 a or b variant models. Approx 27mm or 1 1/8" axle centres.
If you want green rather than grey select the Green Short Tracks or the Black Short Tracks.