The Stridsvagn S1, or Strv S1 for short, is one of the infamous Swedish tank destroyers with their exclusive Travel and Siege mode mechanics, and the only Premium vehicle with those two modes. Furthermore, it has an acute frontal armour. In fact, the armour is at an 'auto-bounce' angle. Don't know what it is? Learn this and more below!
Let's start with the biggest strength of the Strv S1 – the camouflage value. It is extremely difficult to spot, even after shooting, and with a proper set of equipment, crew skills and vehicle camouflage, you can get even more out of it. In return, the view range is extremely low, which is why you need to install a Binocular Telescope (see below), so you are not too dependent on light tanks.
As mentioned before, the Strv S1 is one of the very few vehicles with the Travel and Siege mode. In Travel mode, you can drive forwards or backwards fast, but your gun becomes almost unusable – huge dispersion, no vertical gun aiming and lower rate of fire. Use this mode if you need to change positions or escape from critical situations. Switch into Siege mode and the vehicle becomes super-slow, but the accuracy, aiming time, and even reload time improve immensely. Also, you can move your gun vertically. In this mode, you can attack efficiently from any distance.
The armour layout might be confusing at first, but it's actually quite simple. The frontal angle is so high that incoming AP or APCR shells will automatically bounce off (auto-bounce angle), except if the calibre of the shell is too big. Brawl with medium and light tanks if on a city map, as their shell calibre is smaller, but always keep some distance so as to not get circled.
The spotting mechanics are your biggest weapon. As long as you can spot enemy vehicles yourself and pin them down without getting spotted in return, you're basically untouchable. Also keep in mind that the Strv S1 is one of the very few vehicles that doesn't lose the bonuses of the Binocular Telescope and Camouflage Net while traversing (only in Siege mode).
The choice of crew skills goes in line with the set of equipment. Maximise the view range, and minimise the chance of getting spotted in return. Clutch Braking will help you fend off medium tanks if you are forced to battle in close combat.