| Hardware and OS | Ulefone Armor 21 | Oppo A3s |
| Operating system | Android 13 | Android 8.1 (Oreo); ColorOS 5.1 |
| Processor | Mediatek MT8781 Helio G99 | Octa-core 1.8 GHz Cortex-A53 |
| Chipset | | Qualcomm SDM450 Snapdragon 450 (14 nm) |
| GPU | Mali-G57 MC2 | Adreno 506 |
| RAM | 8 GB | |
| Internal memory | | 16 GB, 2 GB RAM |
| Internal Storage | 256 GB | |
| External memory | | microSD, up to 256 GB (dedicated slot) |
| Memory Card Slot | microSDXC (dedicated slot) | |
| User Interface | Yes | |
| Display | Ulefone Armor 21 | Oppo A3s |
| Type | IPS LCD | IPS LCD |
| Size | 6.58 inches | 6.2" inc |
| Resolution | 1080 x 2408 pixels | 720 x 1520 px |
| Touchscreen | Yes | capacitive touchscreen |
| Screen-to-Body Ratio | | 81.2% |
| Display area | | 95.9 cm2 |
| Display aspect ratio | | 19:9 (height:width) |
| Pixel Density | 401 ppi | 271 PPI |
| Features | 120Hz | |
| Colors | 16M Colors | 16M |
| Connectivity | Ulefone Armor 21 | Oppo A3s |
| 2G Network | | GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2 |
| 5G Network | No | |
| 3G Network | | HSDPA 850 / 900 / 2100 |
| 4G Network | 1, 2, 3, 4, 5, 7, 8, 12, 17, 19, 20, 28, 34, 38, 39, 40, 41, 66 | LTE |
| Wi-Fi | Wi-Fi 802.11 a/b/g/n/ac, dual-band | Wi-Fi 802.11 b/g/n, WiFi Direct, hotspot |
| NFC | Yes | |
| Network | | GSM / HSPA / LTE |
| SIM card | | Dual SIM (Nano-SIM, dual stand-by) |
| Bluetooth | | 4.2, A2DP, LE |
| SIM | Nano SIM | |
| Edge | | Yes |
| Dual SIM | Yes | |
| Wireless Charging | No | |
| GPRS | | Yes |
| GPS | GPS, GLONASS, GALILEO, BDS | Yes, with A-GPS |
| Speed | HSPA, LTE | HSPA 42.2/5.76 Mbps, LTE-A (2CA) Cat6 300/50 Mbps |
| USB | Type-C 2.0 | microUSB 2.0, USB On-The-Go |
| Camera | Ulefone Armor 21 | Oppo A3s |
| Image | 2160p | |
| Main camera | 64 MP (wide), 24 MP (night vision) | 13 MP, Dual |
| Specs | | 13 MP, f/2.2, AF
-2 MP, f/2.4, depth sensor |
| Features | Yes | LED flash, HDR, panorama |
| Video | | 1080p@30fps |
| Selfie camera | 16 MP (wide) | 8 MP, Single |
| Multimedia | Ulefone Armor 21 | Oppo A3s |
| Loudspeaker | Yes | |
| Handsfree | Yes | |
| Video Playback | Yes | |
| Video Out | Yes | |
| 3.5 mm Jack | Yes | Yes |
| Ring Tones | Yes | |
| Radio | Yes | FM radio |
| Design | Ulefone Armor 21 | Oppo A3s |
| Colors | | Red, Dark Purple |
| Dimensions | 176 x 81.6 x 18.1 mm | 156.2 x 75.6 x 8.2 mm |
| Waterproof | IP68/IP69K dust/water resistant (up to 1.5m for 30 min) | |
| Weight | 400 grams | 168 g |
| Battery | Ulefone Armor 21 | Oppo A3s |
| Battery capacity | | 4230 mAh, Non-removable Li-Ion |
| Capacity | Li-Po 9600 mAh, 33W wired | |
| Placement | Non-removable | |
| Other | Ulefone Armor 21 | Oppo A3s |
| Release date | | 2018, July |
| Sensors | Side-mounted fingerprint, accelerometer, proximity, compass, gyro, barometer, | Accelerometer, proximity, compass |
