Swedish M/1905 knapsack | Ränsel M/1905
The Swedish army had since the late 1800s copied a lot of the military equipment design features from the Germans. Not unlike all the other countries nabouring Germany. However they soon adopted their own home grown variant of the German patter and the end result was M/1905 knapsack (or Ränsel in Swedish).
The 1905 (1915) served for the longest time of all the backpack / knapsack designs used by the Swedish army prior to WWII. Apparently the design was altered in 1915 , but it is unclear what was done to the knapsack, as the exterior is identical.
1905 was quite a strange year, as a lot of new and improved equipment was introduced that year. Making me believe the Swedish army underwent a modernisation process. It was also the year that the union between Norway and Sweden seized to exist, and that year Norway elected a Danish prince to become their new king. But that is politics. What concerns us, is the pack in itself.
The knapsack is a semi-rigid construction. The back is one single piece of leather. The sides and front are made of heavy cloth. The entire knapsack is finished with leather trimmings and straps. Buckles, buttons and metal fittings are either steel, aluminium or brass.
The interior is as simple as it gets. Underneath the lid is a large interior "pocket" for a change of clothes (socks, shirt, gloves, scarf, etc). Three smaller cloth flaps fold over one another and secures the contents in the main compartment. The entire interior is covered in cloth.
It is a very high quality knapsack, and it is evident that the stitching is done by hand - not by machine. Although simple in construction, it feels very robust. The only downside being the relatively small carrying capacity. It helps a lot that the mess tin is carried on the front of the pack, but the interior cannot hold more than the reserve rations and clothes.
Charles Lavisse  is very positive about the Swedish equipment, and especially the leather colour of the Swedish equipment as he is not fond of blackened leather:" ...our equipment [France] of black leather is kept in shape with difficulty. There is needed real work and a certain skill to give to it a clean and bright appearance. Then the encaustics used in making its surface, burn and split it. From this fact the leather is used up very rapidly." 
He remarks that the Swedish brown leather is easy to clean and the time previously used for blackening the leather properly could be used for better things.
 See the digital collections of the Swedish armed forces museum: Armémuseum:
 Emile Charles Lavisse was a French officer that, prior to the Great War, travelled Europe and wrote a research rapport on the basic equipment and uniforms on the different European nations.
 Lavisse, Emile Charles, Field Equipment of the European Foot Soldiers 1900-1914, The Imperial War Museum London & The Battery Press Inc. Tennessee, 1994 reprint (1902 orig.), pp. 90-91.
Documentation: Equipment list - 1911
On the left is the equipment list of 1911, where the M/1905 Ränsel is the only knapsack for regular infantry. Engineers are apparently equipped with the M/86 (1886) and sergeants are equipped with the M/01 (1901). There is nothing that indicates, that officers where equipped with any form of backpack / knapsack.