The M113 (Bardehlas) was introduced in Israeli service in 1972 and has been obtained in huge numbers. Estimates are 5500 of all marks. Although the vehicle had more than sufficient mobility, it lacked adequate armour protection. Because the hull was made from aluminium, once hit by an RPG (rocket propelled grenade) fires raged furiously and there was almost no escaping the vehicle. The M113 earned its unofficial name Zippo and crew preferred to ride on the vehicle's roof, taking the risk of exposing themselves to enemy fire rather than staying put in the flammable confines of the Bardehlas.

Just before the start of operation Peace for Galilee (1982) an armour suite was developed for the M113's serving as armoured personnel carriers. The suite consisted of an extra layer of steel plates mounted on a frame welded to the outside of the hull with some 250 mm of space between the hull and the new layer. This suite, the concept of which is called spaced armour, was supposed to protect the hull by letting RPG's explode on the new armour instead of the basic hull.

Although effective to some degree, the plates proved to be very heavy, causing a decline in performance. Rafael Inc. developed a new armour suite, consisting of perforated carbon-steel plates, which were stronger and lighter than the original armour suite. This Toga armour suite is attached to the front and sides of the M113, making it a Zelda. The suite itself is known as Vayzata.

From this basic up armoured vehicle a couple of off springs has emerged, like the Zelda Pikoud, the Kasman and Nagman. Also, armoured ambulances emerged with this extra armour suite.