The R019 / R021 / S021 / S023 - Screw 4P is used in the following:

Exceed R/C - Xtreme
Engine Parts|VX 18cxp
Himoto - ELDORADA E - STARTER VERSION
Himoto - RAPIDA PRO E - STARTER VERSION
Himoto - RAPIDA PRO
Himoto - SYCLONE PRO E - STARTER VERSION
Himoto - PYTHON XV3
Himoto - SYCLONE
Himoto - SYCLONE PRO
Himoto - PYTHON XV3 UPGRADE
Himoto - RAPIDA
Himoto - TAIPAN XRS
Himoto - RAPIDA UPGRADE PRO
Himoto - ELDORADA
Himoto - ELDORADA UPGRADE
Amax - Xtreme
Redcat - Lightning STR
Redcat - Shockwave
Redcat - Tornado BB & S30
Redcat - Volcano SV - S30 - MX
Himoto - VIPER - X2S
Himoto - VIPER XST UPGRADE
Himoto - VIPER XST
Defualt Setups|1/10 scale nitro|1:10 SCALE TWO SPEED NITRO POWERED 4WD OFF - ROAD BUGGY
HSP - Sonic
HSP - Pace Setter
HSP - Atomic
HSP - XSTR Power
HSP - Warhead
HSP - Tyrannosaurus
HSP - Stomer
HSP - Gladiator
HSP - Sidewinder
HSP - Apollo
HSP - Salvager
HSP - Backwash
HSP - Monster
HSP - Starpace
HSP - Hammer
HSP - Wecker
Amax - Howitzer
Amax - Cheetah
Exceed R/C - Mutant
Wind Hobby - Seorider
Redcat - Tsunami
Wind Hobby - Oryx
Wind Hobby - Sport
Amax - Sedrmer
Wind Hobby - Dash
Wind Hobby - Swift
Wind Hobby - Tigris
Engine Parts|SH 18cxp

The R019 / R021 / S021 / S023 - Screw 4P may also be used used in other models please refer to your instruction manual for the correct part.
Actual product may vary from picture.