Sidolówka

Infobox Weapon|is_explosive=yes
name=R wz. 42


caption=Filipinka (right) and sidolówka on exhibition in the Museum of the Warsaw Rising
origin=Poland
design_date=1942
service=1942–1947
type= Offensive fragmentation
filling=c. 250 g of cheddite or amonite
detonation=Timed Friction Fuse
number=350,000
weight=
fill_weight = 250
length=122 mm
diameter=55 mm
variants=various shell types|

Sidolówka (pron. "seedoloovka") was an unofficial, yet common, name of the R wz. 42 hand grenade, produced by the Armia Krajowa in occupied Poland during World War II.

The name of the grenade came from Sidol, a metal-cleaning agent sold in Poland at the time. The first grenades used the Sidol bottles as the coating. Later on the coating was purposely modelled after the bottle in order to allow for easier hiding of the weapon. Sidolówka was first produced in Warsaw in 1942, by the professors of the Warsaw University of Technology under the leadership of Jan Czochralski. It was partially based on an earlier design of the Filipinka grenade, also of underground construction, which in turn was based on a pre-war Polish ET-38 anti-tank grenade. The primer and the detonator were designed by two engineers of the pre-war Polish munition works in Warsaw, pyrotechnician Wadysaw Pankowski and engineer Józef Michaowski.

It was a fragmentation grenade with a P-42 friction primer and a 4.5 second delay time. Until the end of the World War II, an estimate of 350,000 R-42 were produced in Polish underground factories. A large number of such grenades were used in the Warsaw Uprising and other battles of the Operation Tempest.