stations and crew members had to climb on top of the vehicle to use them. The entry method did not change in later production models. The BTR-60B introduced a side door for the gunner on the right side, and firing ports for both the driver and commander, and two for the gunner, one on each side. (For more information on the BTR-60's firing port see the troop compartment section). Both the driver and the commander have forward views through bulletproof windshields, onto which steel covers can be lowered. In the BTR-60P and BTR-60PA, the covers had vision slots, and additional slots on both sides of the crew compartment. These were removed in the BTR-60PB in favor of two periscopes on each side. In early models of the BTR-60P and BTR-60PA, only the driver had a periscope, while the commander had a removable OU-3 infrared searchlight. In the BTR-60PB, both the driver and the commander have three periscopes in the front (the commander's center periscope can be hard to see as it's just below the OU-3 infrared light). The vehicle was usually equipped with an R-113 radio; however, some models used the R-123. The initial BTR-60P production model lacked night-vision and had only four headlights (two infrared, two white, one of each kind per side, these remained in all BTR-60 models). Late BTR-60P models were fitted with night-vision; the TKN-1 connected with the OU-3 infrared searchlight for the commander and the TWN-2 for the driver. This remained unchanged in later models. Troop compartment The troop compartment is behind the crew compartment and in front of the engine compartment. The BTR-60P can transport up to 16 fully equipped soldiers. This number reduced to 14 in BTR-60PB. As the BTR-60P didn't have a roof, it was covered with a tarpaulin when traveling in bad weather conditions. It was also covered with bows and canvas. Also, all BTR-60 models had three firing ports on each upper side of the hull through which the infantry being transported could fire at the enemy with their personal weapons. The difference between models was in the position of these three firing ports. The BTR-60P and BTR-60PA had the firing ports positioned in a row between the middle and the front part of the troop compartment. In the BTR-60PB, the firing ports were relocated; one was next to the driver and commander, one next to the gunner and one